The number 100 expressed as a product of its prime factors is

102 10 squared 22 × 52 2 squared times 5 squared 4 × 52 4 times 5 squared 22 × 25

The prime factorization of 100 is:

2 × 2 × 5 × 5

So, the correct option is:

2^2 × 5^2