Simply. the answer should only contain positve exponets.

That's really an ugly mess.  I'm sure it can be greatly simplified.

                               2 m²  p⁻¹  q⁴  /  m⁴ p⁻¹ q⁴ m² q⁻³

-- There's  m²  on top and also  m²  on the bottom.  They can be cancelled.
-- There's  p⁻¹  on top and also  p⁻¹  on the bottom.  They can be cancelled.
-- There's  q⁴  on top and also  q⁴  on the bottom.  They can be cancelled.

So here's what we have left now:

                                         2              /  m⁴           q⁻³

That's IT !  After only some cancelling.

We can take the  q⁻³  out of the denominator,
and make it  q³  in the numerator.  
And here's what we have now:  

                                       2  q³  /  m⁴   .

And I think that's really the end.
It looks much better now.

Yes you are right the correct answer is b