Candles&Machines Quant Puzzle

How long will Machine Y, working alone, take to produce x candles?

I. Machine X produces x candles in 5 minutes.
II.Machine X and Machine Y working at the same time produce x candles in 2 minutes.

A. I alone sufficient while II alone not sufficient to answer
B. II alone sufficient while I alone not sufficient to answer
C. Either I or II alone sufficient to answer
D. Both I and II are not sufficient to answer
E. Both I and II are necessary to answer

Watch this space for answer in a week.