Reaction of carbonyl compound with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is:

Options

A. a Grignard reagent
B. hydrazine in presence of feebly acidic solution
C. hydrocyanic acid
D. sodium hydrogen sulphite

Explanation

To solve the question regarding which reagent leads to nucleophilic addition followed by elimination of water when reacting with a carbonyl compound, we will analyze each of the given options step by step.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- Carbonyl compounds (aldehydes and ketones) undergo nucleophilic addition reactions. A nucleophile attacks the electrophilic carbon atom of the carbonyl group, leading to the formation of an intermediate.
- In some cases, this intermediate can lose a water molecule, resulting in a condensation reaction.

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