Reggie ate 31 raisins. Which correctly describes 31 as a prime or a composite number and tells the number of factor pairs 31 has? You're choices are: A-31 is a prime number because it has 0 factor pairs. B-31 is a prime because it has 1 factor pair. C-31 is a composite number because it has 1 factor pair. D-31 is a composite number because it has 2 factor pairs.