Answer
c) is correct.
Work Step by Step
The work-energy theorem states that $$W=KE_f-KE_0=\frac{1}{2}m(v_f^2-v_0^2)$$ $W$ is the work done by a net external force on the object
As the theorem indicates, a net external force acting on the particle means there is a change in both the particle's kinetic energy and velocity. Therefore, c) is correct.
