Bauxite `(Al_(2)O_(3).2H_(2)O)` and Aluminosilicate both are ores of aluminium. Bauxite is found on earth but not on Mars whereas Aluminosilicate is found on earth as well as Mars. Possible reason is:

Options

A. No human colony on Mars.
B. No tropical rain forests on Mars.
C. No need of bauxite on Mars
D. Closeness of earth to sun.

Explanation

To solve the question regarding why bauxite `(Al_(2)O_(3).2H_(2)O)` is found on Earth but not on Mars, while aluminosilicate is found on both planets, we can analyze the options provided step by step.

### Step 1: Understand the Composition of Bauxite and Aluminosilicate
- Bauxite is primarily composed of aluminum oxide with water, represented by the formula `Al2O3·2H2O`.
- Aluminosilicate is a mineral that contains aluminum, silicon, and oxygen, typically represented as `AlSiO3`.

### Step 2: Analyze the Conditions for Bauxite Formation
- Bauxite forms through the weathering of aluminosilicate rocks, which requires specific environmental conditions.
- Weathering typically occurs in tropical rainforest environments where there is abundant rainfall, warmth, and biological activity.

### Step 3: Evaluate the Options
1. **No human colony on Mars**: This option is irrelevant to the natural formation of minerals. The presence of humans does not affect mineral deposits.

2. **No tropical rainforest on Mars**: This option is valid. Mars does not have the necessary conditions (like tropical rainforests) that facilitate the weathering of rocks to form bauxite.

3. **No need of bauxite on Mars**: This option is misleading. The absence of bauxite on Mars is not due to a lack of need but rather due to environmental conditions.

4. **Closeness of Earth to the Sun**: This option is incorrect. The formation of bauxite is not directly related to sunlight; it is more about the weathering process.

### Conclusion
Based on the analysis, the correct answer is **Option 2: No tropical rainforest on Mars**. This is the reason why bauxite is not found on Mars, as the necessary conditions for its formation are absent.