Correct Answer: A

Rationale: Opsonization refers to the process by which antibodies bind to the surface of pathogens, marking them for destruction by phagocytes or complement proteins. This coating of antibodies enhances the ability of the immune system to recognize and eliminate the pathogens effectively. Phagocytes (such as macrophages and neutrophils) are better able to engulf and digest pathogens that have been opsonized, as the antibodies attached to the pathogen surface signal to the phagocytes that they are foreign invaders. This process is crucial in the body's immune response to infections and helps in clearing pathogens from the system.

Correct Answer: A

Rationale: A patient with a severe viral infection exhibiting reduced levels of circulating lymphocytes is likely due to the apoptosis of infected lymphocytes. When a virus enters the body, it can infect and replicate within lymphocytes, subsequently triggering the immune system to induce apoptosis in infected cells to prevent further spread of the virus. This process is part of the body's defense mechanism to control the viral infection. As a result, the circulating lymphocyte levels may decrease as infected lymphocytes are targeted for apoptosis. This phenomenon helps to limit viral replication and spread within the body, thereby aiding in the immune response to eliminate the virus.

Correct Answer: B

Rationale: Human chorionic gonadotropin (HCG) can be detected in the blood as early as 10 days after the last menstrual period. This hormone is produced by the placenta shortly after the embryo attaches to the uterine lining. Pregnancy tests detect HCG levels to determine pregnancy status, and the hormone can be detected earlier in the blood compared to urine tests. Detecting HCG in the blood at around 10 days post ovulation is often the earliest point when a blood test can confirm pregnancy.

Correct Answer: D

Rationale: Taking off the room lights and drawing the window shades would provide a calm and soothing environment for the five-year-old patient admitted due to pneumonia with symptoms of cough, respiratory distress, anxiety, and dehydration. By creating a dim and quiet atmosphere, it can help reduce the child's anxiety levels, promote rest and relaxation, and potentially aid in the management of distress caused by pneumonia. Providing a quiet and dark environment can also support the child's comfort and recovery process during the hospital stay.

Correct Answer: A

Rationale: The first responsibility of a nurse when a patient falls is to assess the patient's injury. Assessing the patient's injury immediately allows the nurse to determine the severity of the fall and provide appropriate care and interventions. It is important to assess for any signs of injury, such as pain, swelling, bruising, or altered mobility, and to address any immediate medical needs. Once the patient's injury has been assessed, the nurse can then proceed to report the incident to the head nurse, write an incident report, and notify the physician if necessary.