The systemic circuit:

Innate defenses counter specific disease-causing agents, whereas adaptive defenses include mechanical and chemical barriers.

Choice A is wrong because it confuses the two types of defenses.

Innate defenses are nonspecific and include physical barriers such as the skin, molecules that are toxic to invaders, and phagocytic cells that ingest invaders.

Adaptive defenses are specific and are activated by the innate immune system.

They involve the production of antibodies and specialized cells that recognize and eliminate specific pathogens.

Normal ranges are not applicable in this question as it is about the definitions of innate and adaptive defenses.

Macrophages are the main cells that clear out the cell debris by phagocytosis, a process that involves recognition, engulfment, and degradation of the disposable particles.

Macrophages are professional phagocytes that can be found in various tissues and organs, where they perform efferocytosis, the removal of dead and dying cells.

Choice A is wrong because lymphocytes are not phagocytes, but rather immune cells that mediate adaptive immunity by producing antibodies or killing infected cells.

Choice B is wrong because cytokines are not cells, but rather soluble molecules that regulate inflammation and immunity by acting as signals between cells.

Choice C is wrong because mast cells are not primarily involved in clearing cell debris, but rather in allergic reactions and innate immunity by releasing histamine and other mediators.