Explanation
There are two types of sets: dynamic sets and fixed sets. The members of a dynamic set change when the underlying data changes. Dynamic sets can only be based on a single dimension.
To create a dynamic set:
1) In the Data pane, right-click a dimension and select Create > Set.
2) In the Create Set dialog box, configure your set. You can configure your set using the following tabs:
General: Use the General tab to select one or more values that will be considered when computing the set.
You can alternatively select the Use all option to always consider all members even when new members are added or removed.

None of the other options exist, and therefore are incorrect answers.

Explanation
Measure names and values CANNOT be deleted in Tableau like other columns can. These are auto-generated.
Calculated Fields, and Number of records can both be deleted.

Explanation
From the data pane, simply right click on the dimension, choose geographic role, and then select the appropriate role as follows:

Explanation
The following are the official definitions from the Tableau documentation for the various file types:
1) .tds (Tableau Data Source) - To not contain the actual data but rather the information necessary to connect to the actual data as well as any modifications you've made on top of the actual data such as changing default properties, creating calculated fields etc. (CORRECT ANSWER)
2) .twbx ( Tableau packaged workbook) - To create a single zip file that contains a workbook along with any supporting local file data and background images. This is great for sharing your work with others who don't have access to the original data.
3) Extract (.hyper or .tde) - To create 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.
3) (.twb) Workbooks - To hold one or more worksheets, plus zero or more dashboards and stories.

Explanation
TWBX is all in one. It contains viz, info needed to build the viz, and a copy of the data source. It doesn't contain extracts of the data but can contain both live and data extracts. Best if want to eliminate the barrier of data access.
Create a .twbx with file-based data sources
1) Select File > Save As.
2) Specify a file name for the packaged workbook in the Save As dialog box.

3)Select Tableau Packaged Workbooks on the Save as type drop-down list.
4) Click Save.
5) The default location is the Workbooks folder of the Tableau repository. However, you can save packaged workbooks to any directory you choose.
The following files are included in packaged workbooks:
--> Background images
--> Custom geocoding
--> Custom shapes
--> Local cube files
--> Microsoft Access files
--> Microsoft Excel files
--> Tableau extract files (.hyper or .tde)
--> Text files (.csv, .txt, etc.)