Answer:
Genevieve should use a three digit code instead of a two digit code for her locker combination because a three digit code has more possible combinations than a two digit code, which makes it more secure.
With a two digit code, there are only 100 possible combinations (10 possible digits for the first number and 10 possible digits for the second number). On the other hand, with a three digit code, there are 1,000 possible combinations (10 possible digits for each of the three numbers). This means that it would take a potential thief 10 times longer to guess the correct combination for a three digit code compared to a two digit code, assuming they are using a brute force method of trying all possible combinations.
Therefore, using a three digit code increases the security of the locker and decreases the likelihood of someone gaining unauthorized access.