Compounds with the composition C3H6O can exhibit different functional groups such as ketones, ethers, and alcohols. Let's explore each option in detail:

a) It can be a ketone:
A ketone is a type of organic compound that contains a carbonyl group (C=O) bonded to two carbon atoms. In the given composition C3H6O, if one of the carbons is double-bonded to an oxygen atom, it forms a ketone. The remaining three carbons and six hydrogens can be arranged in various ways to form different ketones.

b) It can be an ether without any pi-bond:
An ether is an organic compound that has an oxygen atom bonded to two alkyl or aryl groups. In the given composition C3H6O, if the oxygen atom is bonded to two carbon atoms without any double bond, it forms an ether. The remaining three carbons and six hydrogens can be arranged in various ways to form different ethers.

c) It can be an alcohol without any pi-bond:
An alcohol is a type of organic compound that contains a hydroxyl group (-OH) bonded to a carbon atom. In the given composition C3H6O, if one of the carbons is bonded to an oxygen atom through a single bond and also has a hydroxyl group, it forms an alcohol. The remaining three carbons and five hydrogens can be arranged in various ways to form different alcohols.

d) It can be an unsaturated ether:
An unsaturated ether is an organic compound that contains a double bond between one of the carbon atoms and the oxygen atom. In the given composition C3H6O, if one of the carbons is double-bonded to an oxygen atom and the remaining two carbons are single-bonded, it forms an unsaturated ether. The remaining three carbons and five hydrogens can be arranged in various ways to form different unsaturated ethers.

In summary, the given composition C3H6O can form compounds with different functional groups such as ketones, ethers, alcohols, and unsaturated ethers. The specific compound formed depends on the arrangement of the carbon and hydrogen atoms within the molecule.