Which is an immune response? The iris of the eye narrows when the eyes are exposed to bright light. Langerhans cells transport harmful substances to white blood cells. Muscles under the skin contract rapidly to adjust the body's internal temperature. T cells signal B cells to adjust the pH of the blood.

T cells signal B cells to adjust the pH of the blood. would be correct i believe.

Option). Langerhans cells transport harmful substances to white blood cells.

Explanation:

An immune response can be defined as a reaction of cells and components of body against the foreign or abnormal substances. Langerhans cells are cells of epithelial membrane of digestive, urogenital, and respiratory tracts.

Langerhans cells represent a type of dendritic cells. Dendritic cells are immune cells that process and represent the antigen or their components on cell surface to the T cells.

Hence, transport of harmful substances by Langerhans cells to the T cells (white blood cells) is an example of immune response.

Thus, the correct answer is second option.