baeyer's reagant reaction

Question

Answer 1

The correct answer is (a)

In Organic Chemistry KMnO₄ is used to form cis-diol from any “ene”-system(double bond) like you asked for cyclohexene. 

There are other reagents for this type of cis addition to double bond to form 1,2-cis diol,like OsO₄,NaIO₄