True or false? Provide proofs, arguments, or instances.
(a) If f'(a) = 0 and f"(a) = 0, f doesn't have the minimum or maximum at a.
(b) The differential equation N'(t) = 1/N(t) explains the growing population.
(c) Derivative of ln(f(x)) equals 1/f(x).
(d) Function sin x is its own 16th derivative.