Final answer:
The Fundamental Counting Principle is used to determine the number of different ways to select a 4-digit PIN for a lock, where the first and last number cannot be zero and repetitions are allowed. The answer is C) 81,000.
Step-by-step explanation:
The Fundamental Counting Principle is used to determine the number of different ways to select items from multiple sets. In this case, we are selecting a 4-digit PIN for a lock, where the first and last number cannot be zero and repetitions are allowed.
There are 9 possible choices for the first and last digit (1-9), and 10 possible choices for the second and third digit (0-9). Since repetitions are allowed, we multiply the number of choices for each digit together: 9 * 10 * 10 * 9 = 8,100.
Therefore, the answer is C) 81,000.