a) and b) are totally inelastic
Work Step by Step
How inelastic a collision is depends on how much the two objects stick. After all, in the first two cases, the objects stick, so they are totally inelastic. However, c) is only mildly inelastic, for the lower velocity indicates that the objects lost some energy by sticking a little bit, but they do end up bouncing off, meaning that it is not totally inelastic.