Which of the infective stage of Ascaris for man ?

Options

A. First larval stage
B. Second larval stage ( rhaditifonn larva )
C. Encysted egg
D. Adult

Answer

To determine the infective stage of Ascaris for humans, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organism**: Ascaris is a type of roundworm that belongs to the phylum Nematoda. It is known to cause infections in the human intestine.

2. **Understand the Life Cycle**: Ascaris does not have an intermediate host. Humans become infected by ingesting the eggs of Ascaris.

3. **Recognize the Infective Stage**: The infective stage of Ascaris for humans is when the eggs contain the second larval stage. This stage is known as the rhabditoid larva.

4. **Mode of Transmission**: Humans acquire the infection by consuming food or water that is contaminated with these infective eggs.

5. **Select the Correct Option**: Given the options provided (1st larval stage, 2nd larval stage, encysted egg, and adult), the correct answer is the second larval stage, as it is the form that is infective when ingested.

### Final Answer:
The infective stage of Ascaris for humans is the **second larval stage** (option 2).

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