Let ∗ be defined on Z⁺ by a ∗ b = a. This operation is:

Let ∗ be defined on Z⁺ by a ∗ b = a. This operation is:

• A. commutative but not associative
• B. associative but not commutative
• C. both commutative and associative
• D. neither commutative nor associative

Answer: B) associative but not commutative

Explanation: a ∗ b = a, b ∗ a = b. Not commutative unless a = b. (a ∗ b) ∗ c = a ∗ c = a. a ∗ (b ∗ c) = a ∗ b = a. So associative.