Final answer:
The nurse should contact the physician and apply physical restraints only as instructed by the physician to address the client's immediate self-harm risk and to ensure proper care and safety measures are followed.
Step-by-step explanation:
In the scenario where a client with schizophrenia is exhibiting increased agitation and self-injurious behavior, and all previous nursing attempts to reduce this behavior have failed, the next step would be A. Contact the physician and apply physical restraints as instructed by the physician. This action ensures that the client's self-harming behavior is immediately addressed to prevent further injury while seeking guidance and orders from the treating physician. Using restraints is a measure taken to protect the client when they are a danger to themselves or others, but it must be done following proper protocol and under a physician's direction to ensure the safety and rights of the client are respected. While placing the client in seclusion or calling security might seem like immediate solutions, these actions should only be taken under specific guidelines and typically require physician orders or institutional policies to be in place before execution. Thus, the nurse's priority is to safeguard the client's well-being while obtaining further instructions from a physician.