Amy's grandmother is exactly 6 6 times older than Amy. Which three statements below must be true? CLEAR CHECK The age of Amy's grandmother is a prime number. The age of Amy's grandmother is a composite number. Amy's age is a factor of the age of her grandmother. The number 6 6 is a factor of the age of Amy's grandmother. The age of Amy's grandmother has exactly two factors. The age of Amy's grandmother has exactly four factors.