The formula for density is divided by volume.

mass

ounces

weight

a) mass

Explanation:

density = mass/volume

Ounces are units of volume. Weight is not the same thing as mass. Weight has to do with gravity. Mass remains constant as a scalar quantity whereas weight is a vector quanitiy. For instance, although you'd have mass in outer space, you would have no weight. The simple answer is because there is no gravity in outer space. Thus, the formula for density is d = m/V.

d.) circle motion requires a force to give it a centripetal acceleration.