If the positive integer x is a multiple of 1 and the positive integer y is a multiple of 7, then xy must be a multiple of which of the following?
I. 7
II. 2
III. 3
Answers.
A) II only  B) I and II only  C) I only  D) II and III only  E) I, II, and III
x=1a   y=7b   xy=7ab   where a,b are integers   Hence , xy will always be divisible by 7 .   I only is the answer.
<result>C</result>
If the positive integer x is a multiple of 1 and the positive integer y is a multiple of 7, then xy must be a multiple of which of the following?
I. 7
II. 2
III. 3