Reduction involves

Options

A. loss of electrons
B. addition of electrons
C. Increasing in oxidation number
D. None of the above

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Reduction**: Reduction is a chemical process that involves a change in the oxidation state of an atom or ion. It is essential to comprehend what reduction means in the context of oxidation-reduction (redox) reactions.

2. **Definition of Reduction**: Reduction is defined as the gain of electrons by an atom or ion. When an atom gains electrons, its oxidation state decreases. This is a fundamental concept in redox chemistry.

3. **Analyzing the Options**:
- **Option A: Loss of electron** - This describes oxidation, not reduction.
- **Option B: Addition of electron** - This correctly describes reduction, as gaining electrons leads to a decrease in oxidation state.
- **Option C: Increasing in oxidation number** - This also describes oxidation, not reduction.
- **Option D: None of the above** - This is incorrect since option B is a valid description of reduction.

4. **Conclusion**: Based on the definitions and analysis of the options, the correct answer is **Option B: addition of electron**.