Litmus is derived from

Options

A. Everina
B. Usnes
C. Parmelia
D. Roccella

Answer

**Step-by-Step Solution:**

1. **Understanding Litmus**: Litmus is a mixture of colored organic compounds that are used as a pH indicator. It changes color in response to the acidity or basicity of a solution.

2. **Source of Litmus**: The colored organic compounds that make up litmus are derived from several species of lichens. Lichens are a symbiotic association between fungi and algae.

3. **Identifying the Fungal Source**: The specific fungal part of lichens from which litmus is extracted is primarily from the genus *Rocella*. This genus is known for its ability to produce the pigments used in litmus.

4. **Litmus Paper**: Litmus is often used in the form of litmus paper, which is filter paper that has been treated with the litmus solution. This paper is used to test the pH of solutions, indicating whether they are acidic or basic.

5. **Conclusion**: Therefore, litmus is derived from the fungal part of lichens, specifically from the genus *Rocella*.

**Final Answer**: Litmus is derived from the genus *Rocella*.

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