One day while measuring acceleration with his pulse as a timing source, Galileo became so excited that his pulse rate increased. His results for acceleration that day were probably .
A. lower than usual.
B. higher than usual.
C. more accurate than usual.
D. unchanged.

A. Lower then usual.

Explanation:

Galileo use pulse as the time source but actually the pulse is stationary and the acceleration changes but how is the acceleration changes (Increased or decreased ) is the main question arises from here.

We know that the acceleration is given by rate of change of velocity with time. If he feels the pulse rate increases means the number of pulse count is more then usual means he take more time to gain the velocity (or to cover the distance). Means time increases as a result acceleration decreases.

So, we can say that acceleration is lower then usual.

the pull of gravity on the rocket decreases

the answer is to check all of them! they all apply well at least i think so!