Characteristic common between Flatworms and Roundworm is

Options

A. Triploblastic
B. Acoelomate
C. Pseudocoelomate
D. Parasitic

Answer

To determine the characteristic common between flatworms (Phylum Platyhelminthes) and roundworms (Phylum Nematoda), we can analyze the options provided:

1. **Triploblastic**: Both flatworms and roundworms are triploblastic organisms. This means they develop from three germ layers: ectoderm, mesoderm, and endoderm. This is a common characteristic of both groups.

2. **Acoelomate**: Flatworms are indeed acoelomate, meaning they lack a body cavity. However, roundworms are not acoelomate; they are pseudocoelomate, which means they have a body cavity that is not completely lined by mesoderm. Therefore, this characteristic is not common between the two.

3. **Pseudocoelomate**: This term refers specifically to roundworms, which have a pseudocoelom (a body cavity that is not fully lined by mesoderm). Flatworms do not possess this feature, so it cannot be considered common.

4. **Parasitic**: While many flatworms are parasitic, there are also free-living species. Roundworms, on the other hand, are primarily parasitic. Therefore, this characteristic is not universally applicable to both groups.

Based on this analysis, the common characteristic between flatworms and roundworms is that they are both **triploblastic** organisms.

### Final Answer:
The characteristic common between flatworms and roundworms is **triploblastic**.