Fats, oils, and steroids are

Options

A. proteins
B. nucleic acids
C. polysaccharides
D. lipids

Explanation

To answer the question "Fats, oils, and steroids are:", we need to identify the category of biomolecules that these substances belong to. Let's break down the options and arrive at the correct answer step by step.

### Step 1: Understand the Components
- **Fats**: These are typically solid at room temperature and are composed of triglycerides, which are formed from glycerol and fatty acids.
- **Oils**: These are usually liquid at room temperature and also consist of triglycerides, but they contain a higher proportion of unsaturated fatty acids compared to fats.
- **Steroids**: These are a type of lipid characterized by a structure of four fused carbon rings. They include hormones like testosterone and cholesterol.

### Step 2: Analyze the Options
1. **Proteins**: These are made up of amino acids and serve various functions such as catalyzing reactions (enzymes), providing structure, and facilitating transport.
2. **Nucleic Acids**: These are the genetic materials of organisms, such as DNA and RNA, which store and transmit genetic information.
3. **Polysaccharides**: These are complex carbohydrates made up of long chains of sugar units, such as starch and glycogen.
4. **Lipids**: This category includes fats, oils, and steroids. Lipids are characterized by being hydrophobic (water-repelling) and non-polar.

### Step 3: Identify the Correct Answer
Given that fats, oils, and steroids are all classified under the same category due to their similar properties, the correct answer is:

**Lipids** (Option 4).

### Conclusion
Fats, oils, and steroids are classified as lipids, which are macromolecules that are hydrophobic and play various roles in biological systems.

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