Answer:
Option D is correct.
Square of binomials.
Step-by-step explanation:
Prove that: 
Square of binomials states that the square of a binomial is always a trinomial.
Also, it will be helpful to memorize these patterns for writing squares of binomials as trinomials.

Take RHS

Apply the square of binomial, we have;

= 4 + 20 + 25 = 24 + 25 = 49 = LHS proved.
Therefore, Square of binomials identity will prove that 