Explanation:
The correct order of the three actions is:
From the connections pane, connect to both data sources
Join both datasets and select the join type
Specify Employee Name as the join key
The first action is to connect to both data sources from the connections pane in Tableau Prep. The connections pane is where you can access and add data sources to your flow. You can connect to various types of data sources, such as Excel, SQL Server, or Tableau Server. In this case, you want to connect to an Excel worksheet and a SQL Server table.
The second action is to join both datasets and select the join type. A join is a way of combining data from two or more tables based on a common field. You can join datasets by dragging one table to the canvas and dropping it on top of another table. This will create a join step in your flow. You can select the join type from the drop-down list on the join step. The join type determines which rows are returned from the tables.
The third action is to specify Employee Name as the join key. A join key is a field that is used to match rows from different tables. You can specify the join key by clicking on the field name in each table and dragging it to the center of the join step. This will create a join clause that shows the field name and the operator. In this case, you want to use Employee Name as the join key, because it is a common field between the two datasets.
The other options are not relevant for this scenario. Specifying Department and Team Size as a join condition will not work, because they are not common fields between the two datasets. Opening both data sources in Tableau Desktop will not help you join them in Tableau Prep. Adding a step to aggregate the data in the SQL Server table will not affect the join, but it may change the level of detail of your data. References:
https://help.tableau.com/current/prep/en-us/prep_connect.htm
https://help.tableau.com/current/prep/en-us/prep_join.htm
https://help.tableau.com/current/prep/en-us/prep_join_types.htm

To create the Position column, you should use the FIRST () function. The FIRST () function returns the number of rows from the current row to the first row in the partition. For example, the first row in a partition will return 0, the second row will return -1, and so on. In this question, the partition is defined by the Segment field, and the table is sorted by the Sales field in descending order. Therefore, the Position column shows the offset of each row from the first row in each segment, based on the sales ranking. References:
Tableau Certified Data Analyst Exam Prep Guide, page 11, section "Creating Calculated Fields" Tableau Help: FIRST Function

Explanation:
we need to create a calculated field that displays the count of returns only for the first year in the table. To do this, we can use the following formula:
IF FIRST () = 0 THEN COUNT (Returns) END
This formula uses the FIRST () function, which returns the number of rows from the current row to the first row in the partition. If the current row is the first row, then FIRST () returns 0. The IF statement checks if this condition is true, and if so, it returns the count of returns for that row. Otherwise, it returns NULL.
To complete the formula in the calculated field, you should select the following options from the drop-down menus:
FIRST ()
0
COUNT (Returns)
https://help.tableau.com/current/pro/desktop/en-us/functions_functions_date.htm