Which statement correctly describes how the period T of a small-angle simple pendulum depends on its length l and the local gravitational field g?
a) T is directly proportional to l and inversely proportional to g.
b) T is inversely proportional to l and directly proportional to g.
c) T is directly proportional to l and inversely proportional to g.
d) T is directly proportional to l and directly proportional to g.