Final answer:
The motion of a rock towed upward and then released is described by a a. parabolic curve. This accounts for the constant downward acceleration due to gravity and fits the characteristics of projectile motion.
Step-by-step explanation:
When Mary tows a rock upward, releases it, and it continues moving upwards before hitting the peak of its trajectory, the curve describing this motion is a parabolic curve. This is because the rock is acted upon by gravity, which imparts a constant downward acceleration to the rock, causing it to slow down as it rises, momentarily stop at the peak, and then accelerate downwards. This type of motion is synonymous with projectiles and is dictated by kinematic equations that describe motion under uniform acceleration, specifically gravity in this case.
A linear curve would imply constant velocity, which is not the case here due to gravity's influence. An exponential curve does not typically describe the motion of projectiles under gravity. A sine curve could describe oscillatory motion, like a pendulum, but not the trajectory of a rock thrown upwards.
Therefore, the correct answer is a) Parabolic curve, which matches the expected trajectory for an object under the influence of gravity without any other forces acting upon it, such as air resistance or additional propulsion.