Discussion
It is not D. D is between 0 and 1 and much closer to zero than to one. The answer is much much bigger than 0 or 1.
It is not B. I can't explain why exactly B is incorrect: I don't know how it was derived. 10^6 is far too small. The E stands for exponent and the exponent is 14 not 6.
A has the right exponent in the wrong place. It is 10 that is raised to the 14th power not the 3.256.
So that only leaves C as the only possible answer. It is C in fact.
Note: in point of fact, the answer is not correct. There is no answer that is totally correct, although C comes closest. It should be 3.456 * 10^11 not 14. I think C intended to be right. You should realize that if you put this into your calculator, you will get 3.456 * 10^11. If you use C you will likely get it right. There is no other answer that works better.