Give the structure corresponding to each IUPAC name. a. 1,2-dimethylcyclobutane b. 1,1,2-trimethylcyclopropane c. 4-ethyl-1,2-dimethylcyclohexane d. 1-sec-butyl-3-isopropylcyclopentane e. 1,1,2,3,4-pentamethylcycloheptane