Which statements about the factors of the terms in the expression 12x+18xy-24y are true? check all that apply/

1.the factors common to 12x and 18xy are 1, 2, 3, 6, x, and y.
2.the factors common to 12x and 18xy are 1, 2, 3, 6, and x.
3.the factors common to 12x and 24y are 1, 2, 3, 4, 6, 12, x, and y.
4.the factors common to 12x and 24y are 1, 2, 3, 4, 6, and 12.
5,the factors common to 18xy and 24y are 1, 2, 3, 6, x, and y.
6,the factors common to 18xy and 24y are 1, 2, 3, 6, and y.
7,the gcf of the expression is 6xy.
8,the gcf of the expression is 6.