You haven't shared the answer choices.
Let's rewrite that first x term: {4x, (1/2)x, 2y, 4, x, 3x), also leaving more space between the answer choices.
I see four x-terms in { 4x, (1/2)x, 2y, 4, x, 3x } . The like terms are {4x, (1/2)x, x, 3x }. There are no other groups of like terms.
