To get the number of different types of awards that have been won, you should use the formula COUNTD({Award}). This formula will return the count of distinct values in the Award field, which are the different types of awards that have been won.
The other options are not correct for this scenario. COVAR({Award}) is not a valid function in Tableau.
MAX({Award}) will return the maximum value in the Award field, which may not be a type of award.
INDEX() will return the index or rank of each row in a partition, which is not related to the types of awards.
References: https://help.tableau.com/current/pro/desktop/en-us/functions_functions_aggregate.htm#COUNTD
https://help.tableau.com/current/pro/desktop/en-us/functions_functions_tablecalculation.htm#INDEX The COUNTD function in Tableau calculates the number of distinct (unique) items in a field. When looking to get the number of different types of awards that have been won, the COUNTD([Award]) function will count each unique award name only once, regardless of how many times it appears in the dataset. This will return the total number of unique award types.

A data source filter is a filter that applies to all the worksheets that use the same data source. It filters the data before any other filters or calculations are applied. You can add a data source filter from the Data Source page by clicking on the Add button next to Filters.
The type of filter that will appear in the Edit Data Source Filters dialog box is a dimension filter on all the sheets. This means that you can choose a dimension from your data source and filter it by values, range, condition, or top/bottom. The filter will affect all the worksheets that use that dimension.
The other types of filters are not data source filters and will not appear in the Edit Data Source Filters dialog box. A table calculation filter is a filter that applies to a table calculation, such as percent of total or running total. A top N condition filter is a filter that shows only the top or bottom N values of a measure or dimension based on a condition. A context filter is a filter that creates a subset of data that other filters can use.

The formula in option B calculates the percent difference in sales relative to the same quarter the previous year. It subtracts the sales of the same quarter from the previous year from the current year's sales, and then divides this by the previous year's sales. This gives a percentage change, which aligns with what is shown in the Calculation field of your dataset. The LOOKUP function returns the value of a specified offset from the current row in the partition. In this case, the offset is -4, which means the value of the same measure four rows above the current row. This corresponds to the same quarter of the previous year, assuming the data is sorted by quarter. References:
LOOKUP Function - Tableau
Table Calculations - Tableau
Tableau Certified Data Analyst Study Guide

check the steps below in explanation.
Explanation:
To modify the bar chart to show the percentage of sales for each Subcategory within every Category, you need to do the following steps:
Open the link to Book1 found on the desktop. This will open the Tableau workbook that contains the CategoryPercentage worksheet.
Click on the CategoryPercentage tab at the bottom of the workbook to open the worksheet. You will see a bar chart that shows the total sales for each Subcategory across all Categories.
Right-click on Sales on the Columns shelf and select Add Table Calculation from the menu. This will open a dialog box that allows you to apply a calculation to your measure.
Select Percent of Total from the Calculation Type drop-down list. This will calculate the percentage of sales for each Subcategory out of the total sales for all Subcategories.
Select Category from the Compute Using drop-down list. This will calculate the percentage of sales for each Subcategory within every Category, instead of across all Categories. The total percentage for every Category will be 100%.
Click OK to apply the table calculation. You will see that the bar chart now shows the percentage of sales for each Subcategory within every Category.
References: https://help.tableau.com/current/pro/desktop/en-us/calculations_tablecalculations.htm
https://help.tableau.com/current/pro/desktop/en-us/calculations_tablecalculations_create.htm
https://help.tableau.com/current/pro/desktop/en-us/calculations_tablecalculations_percentoftotal.htm

To create an image of the chart that you can add to the annual report, you can use either the Export option or the Copy option from the Worksheet menu. The Export option will allow you to save the image as a file in a specified location, name, and format. The Copy option will allow you to copy the image to the clipboard and paste it into another application, such as Microsoft Word. Both options will let you choose which elements to include in the image, such as title, caption, legend, etc. Reference:
Export Views from Tableau Desktop to Another Application
Copy and Paste Views from Tableau Desktop to Another Application