Final answer:
Comparative negligence is the term describing a situation where both a trainer and client share responsibility for the client's injury, with damages apportioned based on each party's level of fault.
Step-by-step explanation:
The legal term used to describe a situation where a trainer fails to act and a client is injured, but the client is determined to have played a role in his or her own injury is D. Comparative negligence. This concept apportions fault among the parties involved. In cases of comparative negligence, both the trainer and the client may be found partly responsible for the injury. The client's compensation for damages will be reduced by the percentage of their contribution to the accident. This contrasts with contributory negligence, where if the client is found to have any fault, they may be barred from recovering any damages.
Comparative negligence is a legal doctrine that allows for the assignment of fault and damages in proportion to each party's degree of negligence. In this situation, both the trainer and the client are considered to have contributed to the injury, and the damages are divided accordingly.