Consider the following statements. (A) Exchange of gases through skin (B) Indirect development (C) Only one genus represents the whole group (D) All the primary chordate features are present in embryo, larva and adult The above features characterise:

Options

A. Urochordata
B. Cephalochordata
C. Cyclostomata
D. Protochordata

Answer

To solve the question, we need to analyze each statement and determine which group of organisms they characterize. Let's break down the statements one by one:

1. **Statement A: Exchange of gases through skin**
- This feature is characteristic of certain organisms, particularly those that have a moist skin surface allowing for gas exchange.

2. **Statement B: Indirect development**
- Indirect development refers to a life cycle that includes a larval stage distinct from the adult form. This is common in many aquatic organisms.

3. **Statement C: Only one genus represents the whole group**
- This suggests that the group in question is represented by a single genus, which is a unique characteristic.

4. **Statement D: All the primary chordate features are present in embryo, larva, and adult**
- This indicates that the organisms in question retain all the key characteristics of chordates throughout their life stages.

Now, let's evaluate the options provided:

- **Urochordata**: This group does not have all the features mentioned, particularly in terms of gas exchange and the presence of features in all life stages.

- **Protocordata**: This group also does not fit since they do not respire through skin and do not exhibit indirect development as described.

- **Cyclostomata**: This group does not have only one genus representing it, as it includes multiple genera.

- **Cephalocordata**: This group fits all the statements:
- They can exchange gases through their skin.
- They exhibit indirect development.
- They are represented by a single genus (e.g., Branchiostoma).
- They retain all primary chordate features throughout their life stages.

Thus, the correct answer is **Cephalocordata**.

### Final Answer:
The above features characterize **Cephalocordata**.