(A ): Mass of a body decreases slightly when it negatively charged.
(R ): Charging is due to transfer of electrons.

Options

A. Both .A. and .R. are true and .R. is the correct explanation of .A.
B. Both .A. and .R. are tru and .R. is not the correct explanation of .A.
C. A. is true and .R. is false
D. A. is false and .R. is true

Answer

To solve the question, we need to analyze the statements given:

**Statement (A):** Mass of a body decreases slightly when it is negatively charged.
**Statement (R):** Charging is due to the transfer of electrons.

### Step-by-Step Solution:

1. **Understanding Statement (A):**
The statement claims that when a body becomes negatively charged, its mass decreases slightly. To evaluate this, we need to consider what happens when a body gains a negative charge.

2. **Charging Mechanism:**
When a body becomes negatively charged, it gains extra electrons. Electrons have a very small mass (approximately \(9.11 \times 10^{-31}\) kg).

3. **Mass Change Calculation:**
If we assume that a body gains 'n' electrons to become negatively charged, the total mass gained by the body can be calculated as:
\[ \text{Mass gained} = n \times m_e \]
where \(m_e\) is the mass of an electron. Since the mass of an electron is extremely small, even if a body gains a significant number of electrons, the overall change in mass will be negligible.

4. **Conclusion for Statement (A):**
The mass of the body does not decrease; rather, it may increase slightly due to the addition of electrons. Therefore, Statement (A) is **false**.

5. **Understanding Statement (R):**
This statement claims that charging is due to the transfer of electrons. This is a fundamental principle of electricity. When electrons are transferred from one body to another, it results in a charge imbalance, leading to the body becoming charged.

6. **Conclusion for Statement (R):**
Since charging indeed occurs due to the transfer of electrons, Statement (R) is **true**.

7. **Final Evaluation:**
Since Statement (A) is false and Statement (R) is true, the correct answer is that A is false and R is true.

### Final Answer:
A is false and R is true.