Which optically active compound on reduction with `LiAlH_(4)` will give optically inactive compound?

Options

A. `{:(CH_(3)-CH-COOH),(" |"),(" "OCH_(3)):}`
B. `{:(CH_(3)-CH_(2)-CH-COOH),(" |"),(" "OH):}`
C. `{:(CH_(3)-CH_(2)-CH-COOH),(" |"),(" "CH_(2)OH):}`
D. `{:(CH_(3)-CH-CH_(2)-COOH),(" |"),(" "OH):}`

Explanation

To solve the question, we need to identify which optically active compound, when reduced with lithium aluminum hydride (LiAlH4), will yield an optically inactive compound.

### Step-by-Step Solution:

1. **Understanding Optical Activity**:
- An optically active compound has at least one chiral carbon atom, which is a carbon atom bonded to four different groups.
- An optically inactive compound lacks chiral centers or has a plane of symmetry.

2. **Analyzing the Options**:
- We have four options, and we need to analyze each one to see if it can yield an optically inactive compound upon reduction.

3. **Option 1**:
- Compound: CH3CHOCH3 (acetaldehyde derivative)
- Upon reduction with LiAlH4, it converts to CH3CH(OH)OCH3.
- This compound has a chiral carbon (attached to CH3, OCH3, H, and OH), thus it is optically active.

4. **Option 2**:
- Compound: CH3CH2CH(OH)COOH (a carboxylic acid)
- Upon reduction, the COOH group converts to CH2OH, yielding CH3CH2CH(OH)CH2OH.
- This compound also has a chiral carbon (attached to CH3, CH2OH, OH, and CH2), making it optically active.

5. **Option 3**:
- Compound: CH3CH2CH(CH2OH)CH3 (a secondary alcohol)
- Upon reduction, it will yield CH3CH2C(CH2OH)CH2OH.
- Here, the carbon that was chiral now has two identical groups (the two CH2OH), which makes it optically inactive.

6. **Option 4**:
- Compound: CH3CH(OH)CH2CH3 (another alcohol)
- Upon reduction with LiAlH4, it will yield CH3CH2CH2CH2OH.
- This compound also has a chiral carbon, making it optically active.

7. **Conclusion**:
- The only compound that, upon reduction with LiAlH4, yields an optically inactive compound is **Option 3**.

### Final Answer:
The optically active compound that on reduction with LiAlH4 gives an optically inactive compound is **Option 3**.