Arrange the following carbanions in order of their decreasing stability.
(A) `H_(3)C-C -=C^(-)`
(B) `H-C-=C^(-)`
(C) `H_(3)C–CH_(2)^(-)`

Options

A. `A gt B gt C`
B. `B gt A gtC`
C. `C gt B gtA`
D. `C gtA gt B`

Explanation

To determine the stability of the given carbanions, we will analyze the hybridization of the carbon atoms and the effects of substituents on their stability.

### Step-by-Step Solution:

1. **Identify the Structures of the Carbanions**:
- (A) `H3C-C≡C^(-)` (Carbanion with a triple bond)
- (B) `H-C≡C^(-)` (Carbanion with a triple bond)
- (C) `H3C-CH2^(-)` (Carbanion with a single bond)

2. **Determine the Hybridization**:
- In (A), the carbon with the negative charge is sp-hybridized because it is part of a triple bond.
- In (B), the carbon with the negative charge is also sp-hybridized for the same reason.
- In (C), the carbon with the negative charge is sp3-hybridized because it is part of a single bond.

3. **Analyze the Electronegativity and Stability**:
- The stability of carbanions is influenced by the hybridization of the carbon atom bearing the negative charge.
- sp-hybridized carbon (like in A and B) has higher electronegativity compared to sp3-hybridized carbon (like in C). Therefore, carbanions with sp-hybridized carbons are generally more stable than those with sp3-hybridized carbons.

4. **Consider the Inductive Effects**:
- In (A), the presence of the `CH3` group can exert a +I (inductive) effect, which can destabilize the negative charge on the adjacent carbon.
- In (B), there are no such groups to destabilize the negative charge, making it more stable than (A).
- In (C), the negative charge on the sp3 carbon is less stable due to the high s-character and the lack of any stabilizing groups.

5. **Order the Stability**:
- From the analysis, we can conclude that:
- (B) is the most stable due to the absence of destabilizing groups.
- (A) is less stable than (B) because of the destabilizing +I effect from the `CH3` group.
- (C) is the least stable due to the sp3 hybridization and lack of stabilizing effects.

### Final Order of Stability:
**(B) > (A) > (C)**