Which one of the following equations of motion represents simple harmonic motion ? <br> Where $k,\; k_0,\; k_1$ and a are all positive

Question

( A ) Acceleration = k(x + a)
( B ) Acceleration = – k (x + a)
( C ) Acceleration = kx
( D ) Acceleration = $-K_{0}$x+$K_{1}$x$^{2}$