Which of the following characters is not related to Aves?

Options

A. Homoiothermy and presence of oil glands in skin
B. Heart is completely three-chambered
C. Respiration is by lungs
D. Exoskeleton is made up of feathers

Answer

To determine which character is not related to Aves, we need to analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Aves**: Aves refers to the class of animals commonly known as birds. Birds have specific characteristics that distinguish them from other classes in the animal kingdom.

2. **Option Analysis**:
- **Option A**: Homeothermy and presence of oil glands in the skin.
- **Explanation**: Birds are homeothermic (warm-blooded), meaning they maintain a constant body temperature regardless of the environment. They also have oil glands that help in feather maintenance. This option is related to Aves.

- **Option B**: Heart is completely three-chambered.
- **Explanation**: This statement is incorrect for birds. Birds have a four-chambered heart, which is a key characteristic that allows for efficient circulation and separation of oxygenated and deoxygenated blood. This option is **not** related to Aves.

- **Option C**: Respiration by lungs.
- **Explanation**: Birds have a highly efficient respiratory system that includes lungs. They utilize air sacs to facilitate a continuous flow of air through their lungs, which is essential for their high metabolic rate. This option is related to Aves.

- **Option D**: Exoskeleton made up of feathers.
- **Explanation**: Feathers are a defining feature of birds, serving various functions including insulation, flight, and display. This option is related to Aves.

3. **Conclusion**: After analyzing all the options, it is clear that **Option B (heart is completely three-chambered)** is the character that is not related to Aves, as birds possess a four-chambered heart.

### Final Answer:
**Option B**: Heart is completely three-chambered.

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