Amy’s grandmother is exactly 6 times older than Amy.
Which three statements below must be true?

1.The age of Amy’s grandmother is a prime number.

2.Amy’s age is a factor of the age of her grandmother.

3.The age of Amy’s grandmother has exactly two factors.

4.The age of Amy’s grandmother is a composite number.

5.The number 6 is a factor of the age of Amy’s grandmother.

6.The age of Amy’s grandmother has exactly four factors.