Where in a data table should units of measurement be shown

Since there are no choices, it will be difficult to answer your question.
But let's say these are the choices:

A. in a separate column after the column of data values
B. in parentheses, in the title of the table
C. in the headings of columns that list the data values
D. in a note next to an asterisk, below the table 

Answer – C (In the headings of columns that list the data values)
 In a data table, units of measurement should be indicated in the headings of the columns where the data values are listed. This shows that the indicated unit applies to all the data values listed in the column.