The way in which some organism supplies some other organism with food and energy known as

Correct Answer: A

Rationale: Food chains describe the linear transfer of energy and nutrients from one organism to another in an ecosystem.

Correct Answer: C

Rationale: The figure (assumed) shows an active plasma B cell at part C, as per the text, typically depicted as antibody-producing.

Correct Answer: C

Rationale: T cells (CD4+) recognize MHCII-antigen complexes and help B cells, unlike antigenic shift (viral reassortment), immature DCs (antigen uptake), or soluble proteins.

Correct Answer: C

Rationale: Isotype switching in germinal centers, driven by CD40 and cytokines, is irreversible and not required for IgM.

Correct Answer: D

Rationale: IL-2 promotes T cell expansion and NK cytotoxicity, but supports (not inhibits) Treg survival.