D is the right answer because g is midpoint of ah and e is midpoint of ab and eg is parallel to bh so eg equals half bh
Without any calculations it's evident it can't be neither B (both numbers are even, so they're divisible by 2) nor C (the numbers end in 0 and 5, so they're divisible by 5).
A.

Both numbers have a factor of 3, so they're not relatively prime.
That means it must be D. But, let's check it.

Indeed, those two numbers are relatively prime.
Answer:
A
Step-by-step explanation:
(3a^4-2a^2+5a-10)-(2a^4+4a^2+5a-2)
a^4-6a^2-8
Both the numerator and denominator are divisible by 6. You need to find the greatest common factor, or GCF, which in this case is 6. So divide both the top and the bottom by 6 and you get 2/-5, and that is your final answer in simplified form.