Answer the following question given this paragraph: 

Note The carbonyl group is ubiquitous in biological compounds. It is found in carbohydrates, fats, proteins, nucleic acids, hormones, and vitamins—organic compounds critical to living systems. In a ketone, two carbon groups are attached to the carbonyl carbon atom. The following general formulas, in which R represents an alkyl group and Ar stands for an aryl group, represent ketones.


Q: In a ketone, two of which kind of groups are attached to the carbonyl carbon atom?

 Choices:

- ions

- nitrogen groups

- oxygen groups

- carbon groups

A:
carbon groups
