An inelastic collision is one in which kinetic energy is not conserved, although momentum is conserved. In the options you provided, the scenario that best describes an inelastic collision is:
A baseball bat hitting a ball.
In this case, some kinetic energy is transformed into other forms of energy (such as sound and heat) during the collision, thus making it inelastic. The other scenarios either involve negligible deformation or do not significantly dissipate kinetic energy in a way that would classify them as inelastic.