The first organism to be found on a bare rock formation is

Options

A. moss
B. lichen
C. fern
D. grass

Explanation

To answer the question "The first organism to be found on a bare rock formation is," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Primary Succession**:
- Primary succession occurs in lifeless areas where there is no soil, such as bare rock formations. It is the process by which biological communities develop over time.

2. **Identifying Initial Colonizers**:
- The first organisms to colonize bare rock are crucial for the establishment of an ecosystem. They help in soil formation and pave the way for other species.

3. **Evaluating the Options**:
- The options provided are:
- A) Moss
- B) Lichen
- C) Fern
- D) Grass

4. **Analyzing Each Option**:
- **A) Moss**: Mosses are non-flowering plants that reproduce by spores. They typically colonize areas after lichens have started the process, so they are not the first.
- **B) Lichen**: Lichens are a symbiotic association between algae and fungi. They are known to be the first organisms to colonize bare rock, making them the correct answer.
- **C) Fern**: Ferns are more developed plants that reproduce using seeds. They require soil to grow, so they cannot be the first colonizers on bare rock.
- **D) Grass**: Grass is a monocot that also reproduces by seeds. Like ferns, they need soil and are not the first organisms on bare rock.

5. **Conclusion**:
- Based on the analysis, the correct answer is **B) Lichen**, as they are the first organisms to colonize bare rock formations during primary succession.

### Final Answer:
The first organism to be found on a bare rock formation is **Lichen** (Option B).