Which one of the following plants is tolerant to selenium ?

Options

A. Astragalus
B. Agrostis tenuis
C. Impatiens balsamia
D. Prosopis juliflora

Answer

To determine which plant is tolerant to selenium, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which plant is tolerant to selenium. Selenium is a trace element that can be toxic in high concentrations, but some plants have developed mechanisms to tolerate it.

2. **Identify the Options**: The options provided are:
- A) Astragalus
- B) Agrosteus teneus
- C) Impatiens balsamia
- D) Prosopis juliflora

3. **Research Plant Families**: It is important to know the families to which these plants belong, as some families are known for their tolerance to certain metals, including selenium.
- **Astragalus** belongs to the **Fabaceae** family.
- **Agrosteus teneus** belongs to the **Poaceae** family (grass family).
- **Impatience balsamia** belongs to the **Balsaminaceae** family.
- **Prosopis juliflora** also belongs to the **Fabaceae** family.

4. **Analyze Selenium Tolerance**:
- **Astragalus**: Known for its tolerance to selenium due to the presence of a compound called methyl selenocysteine, which helps it manage selenium levels.
- **Agrosteus teneus**: As a grass, it does not have the same tolerance mechanisms for selenium and is not known to tolerate it.
- **Impatience balsamia**: This plant does not belong to a family known for selenium tolerance and is not recognized for this ability.
- **Prosopis juliflora**: While it belongs to the Fabaceae family, it is known to have very low tolerance to selenium.

5. **Conclusion**: Based on the analysis, the plant that is tolerant to selenium is **Astragalus**.

### Final Answer:
The correct answer is **A) Astragalus**.