Which expression can be identified and factorised as a difference of two perfect squares, \(A^2-B^2\)?

Correct answer: \(25p^2-16q^2\)

The correct answer is A: \(25p^2-16q^2\). Both terms are perfect squares: \(25p^2=(5p)^2\) and \(16q^2=(4q)^2\). Because they are separated by a minus sign, the expression is \((5p)^2-(4q)^2\). Applying \(A^2-B^2=(A-B)(A+B)\) gives \((5p-4q)(5p+4q)\). Option B is a sum of squares, so the difference-of-squares identity does not apply. Option C is \((5p-4q)^2\), a perfect-square trinomial, because its middle term is \(-2(5p)(4q)=-40pq\). Option D is \((5p+4q)^2\), another perfect-square trinomial. Thus only A has the required structure of two separate squares with subtraction. Expanding its factors cancels the cross terms and returns the original expression. Memory cue: identify the square roots first, then check the sign between the squares.