Final answer:
(A) Ethanol abuse can lead to the excessive production of ketones, a process known as ketogenesis, happening mainly in the liver and potentially leading to ketosis, where the breath may smell sweet like acetone.
Step-by-step explanation:
A substance that someone can abuse which promotes the formation of ketones is ethanol (A).
In certain physiological conditions like starvation, diabetes mellitus, or excessive alcohol consumption, cells may not receive enough carbohydrates leading to increased fatty acid oxidation and subsequently increased acetyl-CoA levels.
When oxaloacetate is low and cannot adequately condense with acetyl-CoA, the latter is diverted to ketogenesis. This process primarily happens in the liver, producing beta-hydroxybutyrate, a primary ketone body.
When ketones are produced in excess, ketosis occurs and can lead to symptoms such as a sweet smell on the breath, similar to the smell of acetone or alcohol.