At what point in its path does a baseball that is hit to the outfield have its minimum vertical speed?
a. as soon as it leaves the bat
b. right before the outfielder catches it
c. at the point where it reaches its maximum height
d. the initial speed of the ball must be known to figure this out

At the point when it reaches its maximum height (answer C)

Explanation:

As soon as the ball leaves the bat is has not only horizontal component of the velocity, but also vertical, which allows it travel upwards in its trajectory.

When it reaches its maximum elevation, and the trajectory starts curving down, is when the velocity of the baseball is just horizontal (the vertical component has been reduced to zero due to the constant action of the acceleration of gravity which was slowing down it ascending pattern.

After that point, the ball starts gaining now vertical velocity being accelerated towards the center of the Earth due to gravity. At the maximum height of its path is when the vertical component of the velocity switches from positive (pointing up) to negative (pointing down) going through zero magnitude.