Identifying general solutions

Which of the following expressions could be a general solution to the equation of motion for an ideal mass-spring system $-k(x - x_{\rm eq}) = m \frac{d^2x}{dt^2}$ ? In a quick phrase or two, explain under what condition(s) each of the expressions could be a solution (answer with a phrase like ``Yes, a general solution if $\omega_1$=...'') or why it can never be:

(a)

$x(t) = x_{\rm eq} + A\cos \omega_1 t$ ;

(b)

$x(t) = C + A_1\sin \omega_1 t + A_2\cos \omega_1 t$ ;

(c)

$x(t) = x_{\rm eq} + A_1\sin \frac{\omega_1}{2} t + A_2\cos \frac{\omega_1}{2} t$ ;

(d)

$x(t) = x_{\rm eq} + A_1 e^{i\omega_ot} - A_2 e^{-i\omega_ot}$ ;

(e)

$x(t) = x_{\rm eq} + A\cos\left[\omega_o (t - t_o)\right]$ ;

(f)

$x(t) = A_1\sin \omega_1 t + A_2\sin \omega_2 t$ ;

(g)

$x(t) = x_{\rm eq} + B\tan \omega_o t + C\sec \omega_o t$;

(h)

$x(t) = x_{\rm eq} - A\cos(\phi_o - \omega_o t)$ ;

(i)

$\frac{d^2 x}{dt^2} = -\frac{k}{m}(x - x_{\rm eq})$ .