If a positive integer n is divisible by both 3 and 7, then n must also be divisible by which of the following?
I. 21
II. 10
III. 63
Choose the correct choice
A) None	B) I only	C) II only	D) I and II	E) II and III
A multiple of 3 and 7 is also a multiple of 21, but not necessarily a multiple of 10 or 63.   The answer is I only.
<result>B</result>
If a positive integer n is divisible by both 3 and 7, then n must also be divisible by which of the following?
I. 21
II. 10
III. 63