ANSWER
The multiplication, CA is defined, and its dimension is 3×2
EXPLANATION
Matrix A is a 2x3 matrix.
Matrix C is a 3×2 matrix.
The product of the two matrices , CA, is defined if and only if the inner product of their dimension are the same.

The inner products are the same.
Hence the matrix multiplication, CA is defined and its dimension is the outer products.

Is 20 and answer because I did this on a calculator and this is the only one to me that would make since
Stop posting on here and do the work yourself I usually don't mind helping people but in some cases, I need to just say do it by yourself look at notes look up the answer there are a million things you can do instead of spam posting all your questions good day
Difference of two squares will be
16y^2 -x^2 = (4y -x)(4y +x)
so the second choice