Hi all, I’m confused with the following question so further explanation

Is appreciated :

If 4x-12≥x+9, which of the following must be true?

(A) X>6

(B) X<7

(C) X>7

(D) X>8

(E) X<8

My answer is C and D ,,, but the book’s answer is A

I see that x>6 could be 6.5 so it’s not true and he didn’t

mention it’s an integer in the question. So C,D must be true.

Am I wrong ?

And does the question which of the following must be true point

To selecting one answer or it is possible to select multiple answers?

(Manhattan book)