The nurse is caring for a client who had an appendectomy 4 hours ago. Which finding requires immediate action by the nurse?

Choice A reason: Redness and edema noted at the incision site are signs of inflammation, which are normal in the early stages of wound healing. The nurse should monitor the site for signs of infection, such as purulent drainage, increased pain, or fever.

Choice B reason: Apical heart rate of 100 to 110 beats/minute is a sign of tachycardia, which may be caused by pain, anxiety, dehydration, or blood loss. The nurse should assess the client's vital signs, fluid status, and hemoglobin level, and administer pain medication as prescribed.

Choice C reason: High-pitched sound heard upon inspiration is a sign of stridor, which is a life-threatening emergency that indicates airway obstruction. The nurse should call for help, administer oxygen, and prepare for intubation or tracheostomy.

Choice D reason: Pain rating of 8 on a scale of 0 to 10 is a sign of severe pain, which may impair the client's recovery and increase the risk of complications. The nurse should administer pain medication as prescribed and use non-pharmacological methods to relieve pain, such as positioning, distraction, or relaxation techniques.

Choice A reason: The humoral immune response is mediated by B cells that produce antibodies against specific antigens. However, this response is not the main problem in AIDS, because B cells are not directly affected by the human immunodeficiency virus (HIV) that causes AIDS. Therefore, this choice is incorrect.

Choice B reason: The cellular immune response is mediated by T lymphocytes that activate other immune cells, such as macrophages, to destroy infected or abnormal cells. This response is the main problem in AIDS, because HIV infects and destroys CD4+ T cells, which are essential for coordinating the cellular immunity. As a result, the client becomes susceptible to opportunistic infections, such as Pneumocystis jiroveci pneumonia. Therefore, this choice is correct.

Choice C reason: Bone marrow suppression of white blood cells can cause immunodeficiency, but it is not the primary cause of AIDS. Bone marrow suppression can occur as a side effect of some drugs or treatments, such as chemotherapy or radiation therapy, but it is not directly caused by HIV. Therefore, this choice is incorrect.

Choice D reason: Exposure to multiple environmental infectious agents can challenge the immune system, but it does not necessarily cause it to fail. The immune system can adapt and respond to different pathogens, unless it is compromised by an underlying condition, such as AIDS. Therefore, this choice is incorrect.