During its life cycle fasciola heptica (Liver fluke) Infects its intermadiate host and primary host at the following larval stages respectively

Options

A. Redia and miracidium
B. Cercaria and redia
C. Metacercaria an cercaria
D. Miracidium and metacercaria .

Answer

To answer the question regarding the larval stages at which Fasciola hepatica (the liver fluke) infects its intermediate and primary hosts, we can break down the life cycle of the liver fluke into clear steps:

### Step-by-Step Solution:

1. **Understanding the Organism**:
- Fasciola hepatica, commonly known as the liver fluke, belongs to the phylum Platyhelminthes, which includes flatworms.

2. **Life Cycle Overview**:
- The liver fluke has a digenetic life cycle, meaning it requires two different hosts to complete its life cycle.

3. **Identifying Hosts**:
- The primary host for Fasciola hepatica is typically sheep or goats, where the adult fluke resides in the bile duct.
- The intermediate host is a snail, which is crucial for the development of the larval stages.

4. **Larval Stages**:
- The life cycle begins when the eggs are released into the water, where they hatch into the first larval stage known as **miracidium**.
- The miracidium then infects the intermediate host, the snail.

5. **Development in the Intermediate Host**:
- Inside the snail, the miracidium develops into the next larval stage, which is the **cercaria**.
- The cercaria eventually leaves the snail and enters the water.

6. **Infection of the Primary Host**:
- The cercaria further develops into the **metacercaria** stage, which is the larval stage that can infect the primary host (sheep/goat).
- When the metacercaria is ingested by the primary host, it develops into the adult fluke in the bile duct.

7. **Conclusion**:
- Therefore, the larval stages at which Fasciola hepatica infects its intermediate host and primary host are **miracidium** for the intermediate host (snail) and **metacercaria** for the primary host (sheep/goat).

### Final Answer:
- The larval stages are **miracidium** (intermediate host) and **metacercaria** (primary host).