Bat , Whale and Human share the following trait

Options

A. Hair
B. Placenta
C. Nocturnal
D. Position of mammary glands .

Answer

To solve the question regarding the shared traits of bats, whales, and humans, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organisms**: We are looking at three organisms: bat, whale, and human. All of these belong to the class Mammalia.

2. **Understand the Options**: The options provided are:
- Hair
- Placenta
- Nocturnal
- Position of mammary glands

3. **Analyze Each Option**:
- **Hair**:
- Bats and humans have hair, but whales, being aquatic mammals, typically do not have hair. Therefore, this option cannot be correct.

- **Placenta**:
- All three organisms (bat, whale, and human) are classified as eutherian mammals, which means they have a placenta. The placenta is crucial for nourishing the developing fetus during pregnancy. This option is likely correct.

- **Nocturnal**:
- Bats are primarily nocturnal, meaning they are active at night. Whales can be active during both day and night, and humans are diurnal (active during the day). Since not all three are nocturnal, this option is incorrect.

- **Position of Mammary Glands**:
- The position of mammary glands varies among these organisms: in bats, they are located on the thoracic wall; in humans, they are on the chest; and in whales, they are near the belly region towards the tail. Thus, this option is also incorrect.

4. **Conclusion**: After analyzing all the options, the only trait that all three organisms share is the presence of a placenta. Therefore, the correct answer is **Placenta**.

### Final Answer:
Bat, whale, and human share the trait of having a **placenta**.