Question

Which of the following is an identity?

Options:

(a) `(p + q)^2 = p^2 + q^2`

(b) `p^2 – q^2 = (p – q)^2`

(c) `p^2 – q^2 = p^2 + 2pq – q^2`

(d) `(p + q)^2 = p^2 + 2pq + q^2`