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 determine which group is characterized by the given statements (A, B, C, D), we need to analyze each statement one by one:

### Step 1: Analyze Statement A
**Statement A:** Exchange of gases through skin.
- This feature indicates cutaneous respiration, which is common in certain chordates, particularly in some protochordates.

### Step 2: Analyze Statement B
**Statement B:** Indirect development.
- Indirect development refers to a life cycle that includes a larval stage. This is found in both Eurochordates (like tunicates) and Cephalochordates (like lancelets).

### Step 3: Analyze Statement C
**Statement C:** Only one genus represents the whole group.
- This statement is true for Cephalochordata, where the genus Branchiostoma represents the entire group.

### Step 4: Analyze Statement D
**Statement D:** All the primary chordate features are present in embryo, larva, and adult.
- The primary chordate features include notochord, dorsal hollow nerve cord, pharyngeal gill slits, and post-anal tail. These features are present in all stages of development in both Eurochordates and Cephalochordates.

### Conclusion
Based on the analysis:
- Statement A (cutaneous respiration) and Statement B (indirect development) are applicable to both Eurochordates and Cephalochordates.
- Statement C (only one genus) applies specifically to Cephalochordates.
- Statement D (presence of primary chordate features in all stages) applies to both groups as well.

However, since Statement C is a unique identifier for Cephalochordates, the features collectively characterize **Cephalochordata**.

### Final Answer
The above features characterize **Cephalochordata**.

---