The answer is 3.

Introduction:
Benzoin condensation is a type of organic reaction in which two molecules of aldehyde condense to form a benzoin compound. This reaction is catalyzed by cyanide ions and typically occurs under basic conditions. In this process, the carbonyl group of one aldehyde acts as a nucleophile and attacks the carbonyl group of another aldehyde, resulting in the formation of a carbon-carbon bond.

Explanation:
Among the given options, all compounds except for (1) Benzene carbaldehyde can undergo benzoin condensation. Let's discuss each compound in detail:

1. Benzene carbaldehyde:
- Benzene carbaldehyde, also known as benzaldehyde, does not have an α-hydrogen atom necessary for benzoin condensation.
- In this reaction, the α-hydrogen atom of the aldehyde acts as a nucleophile and attacks the carbonyl group of another aldehyde.
- However, in benzaldehyde, the α-position is occupied by a benzene ring, which does not have an α-hydrogen atom.
- Therefore, benzene carbaldehyde cannot undergo benzoin condensation.

2. p-toluene carbaldehyde:
- p-toluene carbaldehyde, also known as p-tolualdehyde, contains an α-hydrogen atom necessary for benzoin condensation.
- It can undergo benzoin condensation as the α-hydrogen atom can act as a nucleophile and attack the carbonyl group of another aldehyde.

3. Phenylethanal:
- Phenylethanal, also known as phenylacetaldehyde, contains an α-hydrogen atom necessary for benzoin condensation.
- It can undergo benzoin condensation as the α-hydrogen atom can act as a nucleophile and attack the carbonyl group of another aldehyde.

4. 4-methoxybenzaldehyde:
- 4-methoxybenzaldehyde contains an α-hydrogen atom necessary for benzoin condensation.
- It can undergo benzoin condensation as the α-hydrogen atom can act as a nucleophile and attack the carbonyl group of another aldehyde.

Summary:
In summary, among the given options, benzene carbaldehyde (benzaldehyde) does not undergo benzoin condensation as it lacks an α-hydrogen atom necessary for the reaction. The other compounds, namely p-toluene carbaldehyde, phenylethanal, and 4-methoxybenzaldehyde, can undergo benzoin condensation as they possess the required α-hydrogen atom.

I agree with you its c