A, C, and D, are the correct ones I believe.
Given the following functions below,

Factorising the denominators of both functions,
Factorising the denominator of f(x),

Factorising the denominator of g(x),

Multiplying both functions,
Answer: I think it would be 4a(a−2b squared)
From lowest to highest
22.075, 23.015, 25.085, 25.125