Answer:
assuming you mean commutative, a is the answer
Explanation:
an expression is commutative if you can flip it around and get the same answer.
a + b = b + a
a × b = b × a
example.
commutative: 2 + 3 = 5 = 3 + 2
not commutative: 10 - 3 = 7 but 3 - 10 does not equal 7