Question

a student pushes a tennis ball and a bowling ball with the same force. the tennis ball moves away with a much greater acceleration. this is because:
the bowling ball has a greater mass and therefore a greater acceleration.
the student applied a greater force to the tennis ball.
the forces are equal and opposite, and therefore the accelerations must also be equal.
the tennis ball has less mass, so it has less inertia.

Explanation:

According to Newton's second - law $F = ma$ (force equals mass times acceleration), when the force $F$ is the same, the object with less mass $m$ has a greater acceleration $a$. Inertia is related to mass, and a smaller - mass object has less inertia. The tennis ball has less mass than the bowling ball, so it has less inertia and greater acceleration when the same force is applied.

Answer:

The tennis ball has less mass, so it has less inertia.