Answer:
Diamonds is incorrect, because, the volume of the softball is 8 times the volume of the golf ball
Explanation:
we know that
The volume of a sphere is equal to

where
r is the radius
step 1
Find the volume of the golf ball
we have

substitute

step 2
Find the volume of the the softball
we have

substitute

step 3
Find the ratio of volumes
Divide the volume of the softball by the volume of the golf ball

That means
Diamonds is incorrect, because, the volume of the softball is 8 times the volume of the golf ball