Right choice is (c) The vapour pressure should be less and evaporate easily
Explanation: If the vapour pressure of any drug is more if will get converted into gaseous form and thus through exhalation it will be expelled out of the body. The characteristics of an ideal prodrug are, it should rapidly transform, chemically and enzymatically forming the active product, should have intrinsic pharmacological activity, the vapour pressure should be more and evaporate easily, and apart from an active product other metabolic fragments should be non-toxic.