Which substance is a waxy, starchlike protein that accumulates in tissues and organs under certain pathological conditions?

The correct choice is amyloid, which is a waxy, starchlike protein that can accumulate in tissues and organs due to various pathological conditions, such as amyloidosis. When these proteins misfold, they aggregate into fibrils that deposit in organs, disrupting normal function. This accumulation is often associated with chronic inflammatory diseases and certain types of cancers, leading to significant health issues depending on the organs affected.

In contrast, glycogen is a polysaccharide that serves as a form of energy storage in animals. It does not have the waxy or starchlike characteristics associated with amyloid.

Keratin is a structural protein found in hair, nails, and the outer layer of skin, and is not typically associated with pathological accumulation in the same manner as amyloid.

Collagen is a critical structural protein that provides strength and support to tissues and organs, but it does not have the same waxy, starchlike properties or pathological implications related to misfolding and accumulation as observed with amyloid.