Which of these hydrocarbons is a ketone? Check all that apply. O A skeletal model of a chain beginning with H and continuing with 7 carbons; O is double-bonded to the first carbon in the chain. O A skeletal model of a chain beginning with H and continuing with 3 carbons; O is double-bonded to the first carbon in the chain, and there is a double bond between the second and third carbons. O A skeletal model of a chain of 8 carbons, with O double-bonded to the fourth carbon.