(a) While squeezing a piece of lemon, we use our muscular force using our fingers, to extract its juice. This muscular force acts on the lemon. As a result, the shape of the lemon gets changed.
(b) While taking out paste from a toothpaste tube, we use our muscular force using our fingers. This muscular force acts on the toothpaste tube. As a result, the shape of the tube gets changed.
(c) The suspended load exerts a force on the spring and pushes the spring in the downward direction. As a result of which, the spring gets stretched. Hence, its shape gets changed.
(d) The muscles of the athlete exert muscular force on his body to overcome the frictional force exerted by the ground, as a result of which there is an effect of the force that changes the state of motion of the athlete in the forward direction.