Necturus possesses

Options

A. two pairs of external gills and three pairs of gill slits
B. three pairs each of extenal gills and gill slits
C. four pairs each of external gills and gill slits .
D. two pairs each of external gills and gill slits.

Answer

To solve the question regarding Necturus, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Subject**: We begin by identifying what Necturus is. Necturus is commonly known as the mud puppy, which is a type of salamander.

2. **Understand the Characteristics**: We need to gather information about Necturus, particularly focusing on its respiratory structures:
- Necturus has external gills that are used for respiration in water.
- It also has gill slits that are indicative of its amphibious nature.

3. **Count the Gills and Gill Slits**:
- Necturus possesses **three pairs of external gills**.
- Additionally, it has **two pairs of gill slits**.

4. **Evaluate the Options**: The question provides several options regarding the number of external gills and gill slits:
- Option 1: Two pairs of external gills and three pairs of gill slits.
- Option 2: Three pairs of external gills and three pairs of gill slits.
- Option 3: Four pairs of external gills and gill slits.
- Option 4: Two pairs each of external gills and gill slits.

5. **Select the Correct Answer**: Based on the characteristics identified, the correct answer is that Necturus possesses **three pairs of external gills and two pairs of gill slits**. This matches the description we found.

### Final Answer:
Necturus possesses **three pairs of external gills and two pairs of gill slits**.

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