Which of the following is a monogenetic parasite (has only host in its life cycle) ?

Options

A. Wuchereria bancofti
B. Ascaris
C. Plasmodium vivax
D. Both (A) and (B)

Answer

To determine which of the given options is a monogenetic parasite (a parasite that has only one host in its life cycle), we will analyze each option provided.

### Step 1: Understand the Definition of Monogenetic Parasite
A monogenetic parasite is defined as a parasite that completes its entire life cycle within a single host. This means that it does not require any other host to develop or reproduce.

### Step 2: Analyze Each Option
1. **Wuchereria bancrofti**: This is a parasitic worm that causes lymphatic filariasis. It is a digenetic parasite because it requires two hosts in its life cycle: the human host and the mosquito (vector) for its development and reproduction.

2. **Ascaris**: This is a genus of parasitic worms commonly known as roundworms. Ascaris lumbricoides, for example, is a monogenetic parasite as it completes its life cycle in a single host, which is typically a human.

3. **Plasmodium vivax**: This is a protozoan parasite that causes malaria. It is a digenetic parasite because it requires two hosts: humans and mosquitoes (Anopheles species) to complete its life cycle.

4. **Option a and b**: This option combines the first and second options. Since Wuchereria bancrofti is not a monogenetic parasite, this option is incorrect.

### Step 3: Conclusion
After analyzing all the options, the only correct answer is **Ascaris**, which is a monogenetic parasite.

### Final Answer
The correct answer is **Ascaris** (Option 2).

---