A common hornwort is

Options

A. Anthoceros
B. Funaria
C. Marchantia
D. Riccia.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a common hornwort. Hornworts are a group of non-vascular plants that belong to the division Anthocerotophyta.

2. **Identifying the Options**: The options provided are:
- A) Anthoceros
- B) Funeria
- C) Mercantia
- D) Rhexia

3. **Analyzing Each Option**:
- **A) Anthoceros**: This is indeed a genus of hornworts. Hornworts are characterized by their horn-shaped sporophytes, which is a defining feature of this group.
- **B) Funeria**: This is a genus of mosses, which belong to the bryophytes, not hornworts. Therefore, this option is incorrect.
- **C) Mercantia**: This is a genus of liverworts, which are also non-vascular plants but belong to a different group than hornworts. Hence, this option is incorrect.
- **D) Rhexia**: This is also a genus of liverworts, similar to Mercantia, and does not represent hornworts. Therefore, this option is incorrect.

4. **Conclusion**: Based on the analysis, the correct answer to the question "A common hornwort is" is **A) Anthoceros**.

**Final Answer**: A) Anthoceros

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