(a) Work done by a force acting on an object is equal to the magnitude of the force multiplied by the distance moved in the direction of the force. Work has only magnitude and no direction.
Work done = Force x Displacement = F x S
(b) Zero work.
(c) Kinetic energy of a body moving with a certain velocity is equal to the work done on it to make it acquire that velocity. The expression is K = 1/2 mv^2, where the symbols have their usual meaning.