When there is not sufficient carbohydrate to completely metabolize fatty acids, these molecules form: ?

The right answer is ketone bodies (or ketones).

Ketones refer to certain substances produced during the breakdown of fats in the body.
Much of the acetyl CoA produced by the degradation of fatty acids and glucose is oxidized in the Krebs cycle. However, a fraction of this acetyl CoA is converted in the liver cells into ketone bodies (acetoacetate, D-β-hydroxybutyrate, and acetone).
Ketones are usually eliminated by the kidneys in the urine. But if they are produced in excess and in too high concentration, they become toxic. This is known as ketoacidosis, which usually manifests as a complication of diabetes.

answer: - b cells

explanation: -

there are many types of white blood cells present in our body. one such class of white blood cells are the lymphocytes. the b cells belong to the lymphocyte class of wbcs. the b cells perform their action against the pathogen by producing specialised proteins called as antibodies. these antibodies are produced as and when the b cells encounter pathogens in response to the antigens present on the surface of the pathogen. these antibodies bind to the antigens present on the pathogen and then, target them for destruction by other cells of the immune system.

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.