Acoelomate diploblastic animal phylum is

Options

A. Platyhelminthes
B. Cnidaria
C. Aschelminthes
D. Hemichordata

Answer

To determine the acoelomate diploblastic animal phylum from the given options, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Acoelomate**: Animals that do not have a coelom (body cavity).
- **Diploblastic**: Animals that have two germ layers (ectoderm and endoderm).

2. **Analyze the Options**:
- **A) Platyhelminth**: These are acoelomate but are triploblastic (three germ layers: ectoderm, mesoderm, and endoderm).
- **B) Nidaria**: These are acoelomate and diploblastic (two germ layers).
- **C) Estrelminth**: Similar to Platyhelminth, they are acoelomate and triploblastic.
- **D) Hemichordata**: These are also acoelomate but are triploblastic.

3. **Identify the Correct Answer**:
- From the analysis, only **Nidaria** fits the criteria of being both acoelomate and diploblastic.

4. **Conclusion**:
- The correct answer to the question is **B) Nidaria**.