Okay, let's tackle this question. The patient is a 55-year-old male with Type 2 diabetes, unconscious, high RBS (random blood sugar) of 268 mg/dl, and ketone bodies in blood and urine. The question is asking which substance found elevated in his blood is volatilized by the lungs.

First, I need to recall the pathophysiology of diabetic ketoacidosis (DKA), which seems likely here. DKA occurs when there's a lack of insulin, leading to increased lipolysis and ketogenesis. The liver produces ketone bodies like acetoacetate, beta-hydroxybutyrate, and acetone.

Now, the key point is which of these ketones is volatile and can be exhaled through the lungs. Acetone is known to be volatile and can be exhaled, giving a fruity breath odor. Acetoacetate and beta-hydroxybutyrate are less volatile.

The question is asking for the substance that's volatilized by the lungs. So the correct answer should be acetone. The options aren't listed, but based on the scenario, acetone is the one.

For the incorrect options, if any of the other ketones were present, they wouldn't be exhaled. Also, other substances like glucose or lactate aren't ketones and wouldn't be exhaled.

Clinical pearl: In DKA, acetone breath is a classic sign. Remember the three ketones and which one is volatile. High-yield fact: Acetone is the volatile ketone exhaled in DKA.

**Core Concept**
This question tests understanding of diabetic ketoacidosis (DKA) pathophysiology, specifically the volatile ketone body exhaled via the lungs. DKA occurs due to insulin deficiency, leading to increased hepatic ketogenesis and metabolic acidosis.

**Why the Correct Answer is Right**
In DKA, the liver produces ketone bodies: **acetoacetate**, **beta-hydroxybutyrate**, and **acetone**. **Acetone** is volatile and diffuses into the alveoli, where it is exhaled, causing the characteristic "fruity" breath odor. This exhalation reduces acetone levels in blood, unlike the other ketones, which remain non-volatile. The presence of acetone in breath is a classic clinical clue for DKA.

**Why Each Wrong Option is Incorrect**
**Option A:** Acetoacetate is a non-volatile ketone; it remains in the bloodstream and contributes to acidosis but is not exhaled.
**Option B:** Beta-hydroxybutyrate is the predominant ketone in DKA but is also non-volatile and not volatilized by the lungs.
**Option C:** Glucose is not a ketone and is not exhaled. Hyperglycemia leads to osmotic diuresis, not pulmonary excretion.

**Clinical Pearl / High-Yield Fact**
In DKA, **acetone breath** is a hallmark finding. Remember the "3 ketones of DKA": 1) acetoacetate (acidic, non-volatile), 2) beta-hydroxybutyrate (acidic, non-volatile), and 3) acetone (volatile, exhaled). Acetone

✓ Correct Answer: C. Acetone