Explanation
Phew! Tricky one for sure. This question tests multiple concepts and will help you revise them. We'll be using filters, as well as quick table calculations (percent of total) for this one.
1) Firstly, let's drag Country and to the Rows shelf, and year (discrete) to the Columns shelf.
Then, drag Publications to the Text Icon in the Marks Shelf. The following is our view:

You should save a workbook as a PDF document if you need paper copies of the workbook. A PDF document preserves the layout and formatting of the workbook, and can be easily printed or shared. Saving a workbook as a PDF document is not necessary or useful in the other situations1

Explanation
According to the official Tableau documentation:
Depending on the version the extract was created in, Tableau extract files can have either the .hyper or .tde file extension. Extract files are a local copy of a subset or entire data set that you can use to share data with others, when you need to work offline, and improve performance. For more information, see Extract Your Data.

Explanation
You can create aliases (alternate names) for members in a dimension so that their labels appear differently in the view.
Aliases can be created for the members of discrete dimensions only. They cannot be created for continuous dimensions, dates, or measures.
To create an alias:

1) In the Data pane, right-click a dimension and select Aliases.
2) In the Edit Aliases dialog box, under Value (Alias), select a member and enter a new name.

* To submit your changes: In Tableau Desktop, click OK.
On Tableau Server or Tableau Online, click the X icon in the top-right corner of the dialog box.
When you add the field to the view, the alias names appear as labels in the view. For example:

Joins combine tables by adding more columns of data across similar row structures. This can cause data loss or duplication if tables are at different levels of detail, and joined data sources must be fixed before analysis can begin.

Inner join

Left Join
Blends, unlike relationships or joins, never truly combine the data. Instead, blends query each data source independently, the results are aggregated to the appropriate level, then the results are presented visually together in the view.