Okay, let's tackle this question. The question is about what lactose yields on hydrolysis. So, first, I need to remember what lactose is composed of. Lactose is a disaccharide, right? Disaccharides are made of two monosaccharides linked together. The common ones are sucrose (glucose + fructose), maltose (glucose + glucose), and lactose.

Lactose specifically is found in milk. I think it's made up of glucose and galactose. The enzyme that breaks it down is lactase, which catalyzes the hydrolysis. So when lactose is hydrolyzed, it should split into glucose and galactose. Let me confirm that. Yes, lactose is a β-galactoside of glucose. So the hydrolysis would yield one molecule of glucose and one of galactose.

Now, looking at the options, the correct answer should be glucose and galactose. The other options might be other sugar combinations. For example, sucrose breaks into glucose and fructose, maltose into two glucose. So if any of the options have those, they're incorrect. Also, maybe some options have incorrect sugars like fructose and galactose, which isn't right because lactose doesn't have fructose.

The clinical pearl here is that lactose intolerance is due to deficiency of lactase, leading to undigested lactose causing GI symptoms. So remembering the components of lactose is key for understanding related conditions.

**Core Concept**
Lactose is a disaccharide composed of glucose and galactose linked by a β-1,4 glycosidic bond. Hydrolysis of lactose requires the enzyme lactase to cleave the bond, yielding its constituent monosaccharides.

**Why the Correct Answer is Right**
Hydrolysis of lactose (C₁₂H₂₂O₁₁) produces one molecule of **glucose** and one molecule of **galactose**. This reaction is catalyzed by lactase in the small intestine. Clinically, lactose intolerance arises when lactase deficiency prevents proper digestion, leading to osmotic diarrhea and gas due to undigested lactose fermentation by gut bacteria.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucose + fructose – Incorrect. This describes sucrose hydrolysis, not lactose.
**Option B:** Glucose + glucose – Incorrect. This describes maltose hydrolysis.
**Option C:** Fructose + galactose – Incorrect. Lactose does not contain fructose; galactose is specific to lactose.

**Clinical Pearl / High-Yield Fact**
Remember the "3 Gs" of lactose intolerance: **Gas**, **Gurgling**, and **Gastrointestinal discomfort** after dairy consumption. Lactase supplements (e.g., Lactaid) are used to manage symptoms by pre-digesting lactose into glucose and galactose.

**Correct Answer: D. Glucose and galactose**

✓ Correct Answer: D. One molecule of glocuse and one molecule of galactose