An adolescent male is brought to the emergency department with complaints of excruciating pain in his left testicle. Which of the following should be the priority action by the nurse?

The correct answer is B: Complete an assessment and notify the emergency department physician immediately. This is the priority action because the excruciating pain in the left testicle could be indicative of a serious condition like testicular torsion, which requires urgent medical attention to prevent tissue damage and loss of the testicle. Performing a comprehensive assessment will help gather essential information for the physician to make an accurate diagnosis and provide timely treatment. Options A, C, and D are incorrect as they do not address the urgency of the situation and do not prioritize the patient's immediate medical needs.