The infection of Entamoeba takes place by

Options

A. (a) trophozoites
B. (b) binucleate cyst
C. (c) precystic stage
D. (d) quadrinucleate cyst

Answer

### Step-by-Step Solution:

1. **Understanding the Organism**: Begin by recognizing that Entamoeba is a unicellular eukaryotic organism that can cause infections in humans.

2. **Life Cycle of Entamoeba**: Study the life cycle of Entamoeba, which consists of two main stages: the infective cyst and the trophozoite.

3. **Infective Stage Identification**: Identify the infective stage of Entamoeba. The infective form is the cyst, specifically the quadranucleate cyst, which is formed during the life cycle.

4. **Transmission Route**: Understand how Entamoeba is transmitted. The infection occurs via the fecal-oral route, primarily through contaminated food or water.

5. **Development in the Host**: Once ingested, the cysts reach the small intestine, where they transform into trophozoites. The trophozoites then multiply and can lead to further development of cysts in the lower colon.

6. **Conclusion**: Conclude that the infection of Entamoeba takes place by the quadranucleate cyst, which is the infective stage that enters the host through contaminated sources.

### Final Answer:
The infection of Entamoeba takes place by the quadranucleate cyst.

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