Twelve Hours Post Delivery of Her First Child,the Nurse Is

Twelve hours post delivery of her first child,the nurse is assisting Mrs.Joseph to ambulate to the bathroom.Mrs.Joseph complains of light-headedness and begins to faint.What is the nurse's most important action?

A) Call for immediate assistance
B) Ensure the client's modesty
C) Prevent the client from hitting her head
D) Check vital signs