When a partition is formatted with a file system and assigned a drive letter it is called a volume?

lookup functions allow spreadsheet users to :

Show quantities of distinct, discrete categories of Data ( A )

Explanation:

The lookup function in a spreadsheet returns values from a range or an Array usually a row from the spreadsheet or a column from the spreadsheet been queried.

The best description for the lookup function in the options provided is the option that show quantities of distinct, discrete categories of data. because from the definition of the lookup function the data returned is a discrete and distinct one because it is returned from a range or an array in the spreadsheet.