It was a D. Perfectly inelastic collision.
A perfectly Inelastic collision is the case while our bodies that collide, flow at an equal pace after the collision. An elastic collision is a collision in which both Kinetic strength and Momentum are conserved. An Inelastic collision is a collision in which Momentum is conserved, but Kinetic strength isn't always.
A perfectly elastic collision is described as one wherein there's no loss of kinetic energy within the collision. An inelastic collision is one wherein part of the kinetic power is modified to some different shape of power within the collision.
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