Why Are Multiple NAND Gates Often Used in Place of Other

Multiple Choice

Why are multiple NAND gates often used in place of other single function gates?

A) It is easier to design logic circuits with a single gate type, since you only have to fully understand how one type of gate works.
B) It makes it possible to use spare portions of NAND IC packages to implement other logic functions, perhaps reducing the total IC package count.
C) NAND gates are cheaper than any other type of gate.
D) NAND gates are packaged more densely on IC's than other types of gates.