The tympanic cavity in frog communicates with pharynx through:

Options

A. Bidder's canal
B. Horizontal canal
C. Semicircular canal
D. Eustachian tube

Answer

To solve the question regarding the communication of the tympanic cavity in frogs with the pharynx, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Tympanic Cavity**: The tympanic cavity is an air-filled space located in the middle ear of frogs. It plays a crucial role in hearing.

2. **Identifying the Communication Pathway**: The question asks how this cavity connects to the pharynx. The pharynx is a part of the throat that is involved in both the digestive and respiratory systems.

3. **Evaluating the Options**:
- **Option 1: Horizontal Canal**: This option is incorrect as the horizontal canal is related to balance and does not connect the tympanic cavity to the pharynx.
- **Option 2: Semicircular Canals**: This option is also incorrect. Semicircular canals are involved in balance and spatial orientation, not in communication with the pharynx.
- **Option 3: Eustachian Tube**: This is the correct option. The Eustachian tube connects the tympanic cavity to the pharynx, allowing for pressure equalization and drainage.

4. **Conclusion**: The tympanic cavity in frogs communicates with the pharynx through the Eustachian tube.

### Final Answer:
The tympanic cavity in frogs communicates with the pharynx through the Eustachian tube.

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