An object is present on the principal axis of a concave mirror at a distance `30cm`from it.Focal length of mirror is`20cm`
If object starts moving with `2cms^(-1)` along principal axis towards the mirror then
A. image starts moving with`8cms^(-1)`away from the mirror
B. image starts moving with`8cms^(-1)` towards the mirror
C. image starts moving with`4cms^(-1)`towards the mirror
D. image starts moving with`4cms^(-1)`away from the mirror
