The infective stage in the life-cycle of ascaris is or the infection is brough by

Options

A. Tetranuleated cyst
B. miracidium
C. Embryonated egg
D. Cysticercus larva

Answer

### Step-by-Step Solution:

1. **Understanding Ascaris**: Ascaris is a type of roundworm that causes a disease known as Ascariasis in humans. It is important to note that Ascaris follows a single-host life cycle, meaning it does not require another host to complete its development.

2. **Life Cycle of Ascaris**: The life cycle begins when the embryonated eggs are discharged from the feces of an infected human. These eggs are then released into the soil.

3. **Development in Soil**: In the soil, the eggs undergo development and hatch into larvae. The larvae go through different stages, specifically Larval 1 and Larval 3 stages.

4. **Infection Process**: The infective stage occurs when a human ingests the embryonated eggs. These eggs are resilient and can survive outside the host until they are consumed.

5. **Entry into the Host**: Once ingested, the eggs travel to the gastrointestinal tract of the human, where they hatch and develop into adult worms.

6. **Adult Worms**: The adult Ascaris worms grow in the GI tract and can invade the bloodstream, leading to further complications and the release of more eggs into the environment through feces.

7. **Identifying the Infective Stage**: The infective stage of Ascaris is specifically the embryonated egg, which is the stage that leads to infection when ingested by a human.

### Conclusion:
The infective stage in the life cycle of Ascaris is the **embryonated egg**.

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