The correct answer is B. NAND.
A functionally complete set of logic gates is a set of gates that can be used to create any other logic gate. The three basic logic gates are AND, OR, and NOT. Any other logic gate can be created using these three gates.
NAND is a logic gate that produces a 1 output only if all of its inputs are 0. This means that NAND cannot be used to create an AND gate, which produces a 1 output only if all of its inputs are 1. Therefore, NAND is not a functionally complete set.
AND, OR, and NOT are all functionally complete sets. This means that any other logic gate can be created using these three gates. For example, an OR gate can be created by connecting two AND gates in parallel. A NOT gate can be created by connecting an AND gate to itself.
E is not a correct answer because it is not a question.