A baseball would hit the bat harder. This is because the baseball is a lot heavier and more dense than the plastic ball. The keyword that you're looking for is density. The baseball is dense.
I literally looked everywhere for the answer, and I still found nothing. I hope you get it right. Sorry.
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ANSWER
C. 
. newtons
EXPLANATION
According to Newton's second law,
, where
is the mass measured in kilograms.
and
is the acceleration in metres per second square.
We substitute these values to obtain,
.
We rearrange to get,
.
We multiply out the first two numbers and leave our answer in standard form to get,
.
The correct answer is C
