What is the iron-containing component of a red blood cell?.

Choice A rationale:

Hemoglobin is an iron-containing biomolecule that binds oxygen and is responsible for the red color of the cells and the blood. -

Choice B rationale:

Hematocrit is not an iron-containing component, but rather a measure of the proportion of blood volume that is occupied by red blood cells. -

Choice C rationale:

Cytoplasm is the fluid inside the cell where cellular components are suspended, but it does not contain iron. -

Choice D rationale:

The nucleus is not present in mature red blood cells.

Choice A rationale:

Innate immunity is not an acquired immunity. Acquired immunity refers to immunity that develops after exposure to a specific pathogen.

Choice B rationale:

Innate immunity does not retain a memory of a pathogen after defeating it. This is a characteristic of adaptive immunity.

Choice C rationale:

Innate immunity does not offer protection against a particular pathogen. It provides a general defense against a wide range of invaders.

Choice D rationale:

Innate immunity is present at birth. It provides a fast response that involves first- and second-line defenses.