Explanation

(c)
The term hexose refers to the presence of six carbon atoms and term keto shows the presence of ketonic group. Thus, the compound which contains 6 C atoms and one > C = O group is called ketoheoxse. Among the given only glucose and fructose are six C compounds. Out of them, glucose contains an aldehyde group while fructose contains a ketonic group. Hence, the example of ketohexose is fructose.