Which type of reactions are favoured by carbonyl compounds? 

Nucleophilic addition reactions

The correct answer is option 2. Nucleophilic addition reactions.

The reaction of the carbonyl group generally involve the formation of bonds with electron deficient carbonyl carbon. The electron rich , i.e., nucleophile will attack at carbonyl carbon in the rate determining step and therefore, these reactions are known as nucleophilic addition reactions. They can be represented as: