What material is found in the hollow spaces of long bones?

A. Memory T cell: Memory T cells are important for the adaptive immune response and provide cellular immunity but are not responsible for producing antibodies.

B. Memory B Cell: Memory B cells remain in the body after an infection has been cleared and are responsible for producing specific antibodies upon re-exposure to the same pathogen.

C. Natural killer cell: Natural killer cells are part of the innate immune system and function to kill virally infected cells and tumors but do not produce antibodies or have memory capabilities.

D. Mast cell: Mast cells are involved in allergic reactions and defense against parasites but do not produce antibodies and are not part of the memory response.

A. Increased surface tension: This would decrease ventilation as it increases the force needed to expand the lungs.

B. Increased lung compliance: Compliance refers to how easily the lungs can expand. Increased compliance makes it easier for the lungs to inflate, thereby increasing ventilation.

C. Fewer alveolar sacs: Having fewer alveolar sacs reduces the surface area for gas exchange, which would likely reduce ventilation efficiency.

D. More airway resistance: Increased airway resistance makes it harder to breathe, so it would reduce ventilation rather than increase it.