Answer:30 cm
Explanation:
Given
object distance 
focal length of concave mirror 
height of object 
Using mirror formula




and magnification is



So height of object is same as of object .
Position :image is formed at the spot where object is placed.
It's not in motion when the line straight and flat . there's #9
For acceleration, there needs to be three factors that come into play. Either the change in velocity is increasing, decreasing, or it is changing direction. On a circular track, the direction is always changing. Which fits one of the three factors. So your answer would be A.