Which one of the following statements is incorrect

Options

A. In cockroaches and prawns excretion of waste material occurs through Malpighian tubules.
B. In ctenophores, locomotion is mediated by comb plates.
C. In fasciola flame cells take part excretion
D. Earthworms are hermaphrodites and yet cross fertilisation take place among them.

Explanation

To determine which statement is incorrect, let's analyze each option provided in the question step by step.

### Step 1: Analyze the first statement
- The first statement claims that in cockroaches and prawns, excretion of waste material occurs through Malpighian tubules.
- **Analysis**: Malpighian tubules are indeed the excretory structures found in most insects, including cockroaches. However, in crustaceans like prawns, the excretory function is performed by green glands, not Malpighian tubules.
- **Conclusion**: This statement is incorrect.

### Step 2: Analyze the second statement
- The second statement mentions that in Ctenophores, locomotion is mediated by the comb plates.
- **Analysis**: Ctenophores (also known as comb jellies) do have comb plates (or ctenes) that are used for locomotion. This statement is true.
- **Conclusion**: This statement is correct.

### Step 3: Analyze the third statement
- The third statement states that in Fasciola, the flame cells participate in excretion.
- **Analysis**: Fasciola, commonly known as liver flukes, do possess flame cells which are involved in excretion. This statement is true.
- **Conclusion**: This statement is correct.

### Step 4: Analyze the fourth statement
- The fourth statement claims that earthworms are hermaphrodites and yet cross-fertilization takes place among them.
- **Analysis**: Earthworms are indeed hermaphrodites, meaning they possess both male and female reproductive organs. However, they typically engage in cross-fertilization with another earthworm during reproduction. This statement is true.
- **Conclusion**: This statement is correct.

### Final Conclusion
Based on the analysis:
- The incorrect statement is the first one: "In cockroaches and prawns, excretion of waste material occurs through Malpighian tubules."