Character which is closely related to human evolution:

Options

A. Disappearance of tail
B. Reduction in size of jaws
C. Binocular vision
D. Flat nails

Answer

To solve the question regarding the characters closely related to human evolution, we will analyze each option provided:

1. **Disappearance of tail**:
- In the evolutionary history of humans, the loss of a tail is indeed a significant change. However, this trait is not as closely related to the evolution of modern humans compared to other characteristics.

2. **Reduction in size of jaws**:
- This is a key characteristic of human evolution. Over time, as humans evolved, there was a notable reduction in the size of the jaws and the length of jaw bones. This change is associated with dietary shifts and the development of tools for food preparation. Additionally, the shape of teeth has evolved from a U-shape to a more semicircular form, which is also indicative of this reduction.

3. **Binocular vision**:
- While binocular vision is an important adaptation for depth perception and is present in many primates, it is not a unique characteristic that distinguishes human evolution specifically.

4. **Faked nails**:
- Humans have flat nails instead of claws, which is a characteristic of primates. However, this trait is not as closely tied to the evolutionary changes that define modern humans compared to the reduction in jaw size.

Based on the analysis of these options, the character that is most closely related to human evolution is:

**Answer: b. Reduction in size of jaws.**