Answer: The correct option is d.
Explanation: Empirical formula is a chemical formula which has the simplest ratio of elements present in a chemical compound.
From the given following pairs, the pair which shares the same empirical formula is

Empirical formula of
is
(by dividing the coefficients of
by 3)
Empirical formula of
is
(by dividing the coefficients of
by 3)
Both the chemical formulas have same empirical formula. Hence, the correct option is d.