$ A simple but dominant gametophyte is called Prothallus.
! Prothallus is found in Bryophytes.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the question regarding the assertion and reason provided, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
The assertion states: "A simple but dominant gametophyte is called Prothallus."

- **Understanding Prothallus**: Prothallus is indeed a gametophyte, but it is primarily associated with pteridophytes (ferns), not bryophytes. In ferns, the prothallus is the heart-shaped structure that develops from the germination of spores and is the dominant phase of the life cycle.
- **Dominance**: In the context of plant life cycles, the gametophyte is dominant in bryophytes (like mosses), while in pteridophytes, the sporophyte is the dominant phase. Therefore, the assertion is incorrect.

### Step 2: Analyze the Reason
The reason states: "Prothallus is found in Bryophytes."

- **Understanding Bryophytes**: Bryophytes (like mosses and liverworts) have a dominant gametophyte stage, but the structure referred to as prothallus is not found in them. Instead, prothallus is characteristic of pteridophytes (ferns). Thus, this statement is also incorrect.

### Step 3: Conclusion
Since both the assertion and the reason are incorrect, we can conclude:

- **Assertion**: Incorrect
- **Reason**: Incorrect

### Final Answer
Both the assertion and the reason are wrong.