Pls help I need a good grade

Hello~
I used Cymath for this!
https://www.cymath.com/answer?q=(0.4%20*10%5E-6)%20(0.7%20*%2010%5E-2)
In short the answer is B.
The link has the step by step answers!
I highly recommend this sight by the way, its always correct!
Ary~