If a function has differential coefficient that vanishes for all values of x in the interval A<=x <=b, the function is?

A discontinues function

A continues function

Constant

None of these

Explanation

If the differential coefficient (derivative) of a function is zero for all $x$ in an interval $[a, b]$ , it means the function has no change in that interval.

This implies the function is constant over the entire interval.