Which of the following is an incorrect statement regarding Plasmodium falciparum ?

Options

A. It causes malignant malaria
B. It is transmitted by mosquito
C. It is a helminth
D. It may be fatal

Answer

To determine which statement regarding Plasmodium falciparum is incorrect, we will analyze each option provided in the question.

1. **Statement 1: It causes malignant malaria.**
- Plasmodium falciparum is indeed known to cause malignant malaria, which is the most severe form of malaria. This statement is **correct**.

2. **Statement 2: It is transmitted by mosquito.**
- Plasmodium falciparum is transmitted through the bite of infected female Anopheles mosquitoes. This statement is also **correct**.

3. **Statement 3: It is a helminth.**
- This statement is **incorrect**. Plasmodium falciparum is not a helminth; it is a protozoan parasite belonging to the genus Plasmodium. Helminths are a different group of organisms, typically referring to parasitic worms.

4. **Statement 4: It may be fatal.**
- Plasmodium falciparum can indeed lead to severe complications and can be fatal if not treated properly. This statement is **correct**.

After analyzing all the statements, we find that the **incorrect statement** regarding Plasmodium falciparum is **Statement 3: It is a helminth.**

### Summary of the Solution:
- Statement 1: Correct (causes malignant malaria)
- Statement 2: Correct (transmitted by mosquito)
- Statement 3: Incorrect (it is a protozoan, not a helminth)
- Statement 4: Correct (may be fatal)

### Answer:
The incorrect statement is: **It is a helminth.**