Here is a little tip for this: The unit above cancels the unit below. So in this problem you are asked to convert pounds to ounce. So your equation will look like this.
ounce = 2.93 pounds

Your ratio should involve the conversion factor. So 16 and 1 is involved canceling A and D. Then, Notice that you started with poubls. Then the ratio must have pounds at the bottom to cancel the units leaving ounces.
Answer:
I think it might be the 2 one
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.