One indication that a planet may exist near a distant star is that

Shadows blocking part of the light from the star.

A quick warning though this only works on planets either close to the star or planets that are very large. 

Also to ensure that the shadows are planets the shadows have to move or orbit around the star. IE The shadow moves

The ball continued moving in the same direction and its speed increased.

When John kicked the ball, this was an example of motion. The ball's force increased because the ball got force from John's leg. So, the answer is option A.

Hope this helps you!