Which of the Following Rules Should Be Followed When Constructing

Which of the following rules should be followed when constructing tables?

A) The question mark sign should be used to indicate unavailable data in a table.
B) Footnote references to numbers in a table should be keyed with superscript numbers.
C) The zero (0) should be used to indicate unavailable data in a table.
D) Totals and subtotals should always appear either at the right or at the bottom of a table.
E) The units in which the data are recorded should be clearly mentioned in the table.