B cells are the part of the immune system that produces antibodies, the proteins that recognize and neutralize pathogens. When B cells don’t function properly, the body can’t mount an adequate antibody response to infections or vaccines, leading to little or no antibody production. That’s why the correct answer is a lack of an antibody response. The other options don’t reflect how B cells work: hairlessness isn’t caused by B cell function, absence of the spleen is a structural issue unrelated to antibody production, and wasting disease is a general condition not specifically tied to B cell defects.

In decentralized management, authority and resources are distributed to individual departments rather than channeled through a single central office. Each department has control over its own facility and operating budget, allowing it to plan maintenance, space use, and day-to-day operations to fit its specific needs. This autonomy supports quicker, department-level decision-making and tailored services, equipment, and staffing. The other statements describe centralized aspects—centralized purchasing, a single supervising department, or a shared inventory system—none of which align with the idea of departmental self-management.

Protecting immunocompromised animals relies on layered protections that combine environmental, engineering, and personal measures. A room with positive pressure helps keep outside contaminants from entering the animal area by pushing air out when doors are opened, reducing the chance of pathogens reaching the animals. Personal protective equipment acts as a barrier between staff and animals, lowering the risk of transfer of infectious agents. Cage change cabinets provide a controlled, clean-air environment during routine cage changes, minimizing aerosol spread and protecting both the animals and staff. When these controls are used together, they offer multiple, overlapping defenses against infection, which is essential for vulnerable animals. That’s why all of these measures are used to protect immunocompromised animals.

After the first exposure to an antigen, the immune system creates memory B cells that persist over time. When a booster injection is given, these memory cells are quickly re-stimulated and produce a larger amount of antibody, often with higher affinity, leading to a higher antibody titer in the blood. This is the secondary immune response, which is faster and stronger than the initial response. Exposing the animal to disease is not a controlled or safe way to raise titers, and antibiotics do not stimulate antibody production. It’s incorrect to say titers cannot be raised after the initial injection—the booster is exactly what raises them by reactivating the immune memory.