To determine which one is a homopolymer, we need to understand the definition of a homopolymer and analyze the options provided.
### Step-by-Step Solution:
1. **Understand the Definition of Homopolymer**:
A homopolymer is a polymer that is made up of only one type of monomer unit. In contrast, a heteropolymer is made from two or more different types of monomer units.
2. **Evaluate the Options**:
- **Protein**: Proteins are made from different amino acids, hence they are not homopolymers.
- **Lipids**: Lipids, such as triglycerides, are not polymers in the traditional sense and do not consist of repeating monomer units, so they are not homopolymers.
- **Polysaccharides**: Polysaccharides can be either homopolysaccharides (made from one type of sugar) or heteropolysaccharides (made from different sugars). Therefore, this option is too broad.
- **Cellulose, Inulin, and Polypeptide**: Cellulose is a polymer of glucose, and inulin is a polymer of fructose. However, polypeptides are made from different amino acids, so this option includes a non-homopolymer.
- **Inulin, Chitin, and Pectin**: Inulin is a homopolymer of fructose, and chitin is a homopolymer of N-acetylglucosamine. Pectin, however, is a heteropolymer.
- **Starch, Cellulose, Glycogen, and Inulin**: Starch, cellulose, and glycogen are all homopolymers made from glucose, while inulin is a homopolymer of fructose.
3. **Identify Homopolymers**:
- From the analysis, we see that starch, cellulose, glycogen, and inulin are all homopolymers.
- Chitin is also a homopolymer of N-acetylglucosamine.
4. **Conclusion**:
The correct answer to the question "Which one is a homopolymer?" includes starch, cellulose, glycogen, and inulin as they are all made from a single type of sugar.
### Final Answer:
Starch, cellulose, glycogen, and inulin are homopolymers.
