I just need help knowing how many possible outcomes there are for (a).

A person is driving home from work. On his way home, he must pass three crossroads. For each crossroad, he's expected to see a red (R), a green (G), or a flashing yellow (Y) for the traffic lights. (a) Recall that S is all the possible traffic lights he might see for 3 crossroads. (b) List all outcomes in event B that he sees three same colored light for 3 crossroads: (c) List all outcomes in event C that he sees exact 2 red lights: (d) List all outcomes in event D that he sees 2 lights in the same color