For a,e,d are the positive integers, and d|a means that “a is divisible by d”, if d|ae, which of the following must be true?  Choose the most appropriate option:
A) d|a  B) d|e  C) d|2ae  D) d|(a+e)  E) d|(a-e)
d/a means a is divisible by d   d/ae means ae divisible by d.   all are integers so ,   if ae is divisible by d,   1 a can be divisible by d   or   2 e can be divisble by d.   so the question stem asks must true.   so option a and b are could but not must.   option c is 2ae divisible by d. if ab is divisible by d then 2ae is divisible by d.   option d and e we can't predict.   so option d|2ae is correct.
<result>C</result>
For a,e,d are the positive integers, and d|a means that “a is divisible by d”, if d|ae, which of the following must be true?