The ancestors of modern day frogs and salamanders are

Options

A. Coelacanth
B. Amphioxus
C. Jawless fish
D. Hemichordata

Answer

To solve the question regarding the ancestors of modern-day frogs and salamanders, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the ancestors of modern-day frogs and salamanders. We need to identify which of the given options is the most closely related to these amphibians.

2. **Analyze the Options**:
- **Coelacanth**: This is a type of fish that is considered a connecting link between fishes and amphibians. It has both fish-like and amphibian-like characteristics.
- **Amphioxus**: This organism is a type of lancelet and is considered a primitive chordate, but it is not directly related to amphibians.
- **Jawless Fish**: These are primitive fish that do not have jaws and are more closely related to the early evolution of vertebrates.
- **Hemichordata**: This is a separate phylum and does not directly relate to amphibians.

3. **Identify the Correct Answer**: Given that coelacanths have characteristics that bridge the gap between fish and amphibians, they are the most relevant ancestors to modern frogs and salamanders.

4. **Final Conclusion**: The correct answer is **coelacanth**.