Swern oxidation requires COCl2, triethylamine, and DMSO. The same reaction can be accomplished using PCC and dichloromethane. This reaction oxidizes an alcohol to a carbonyl, but only works with primary and secondary alcohols.

The starting material first needs to be brominated, which occur at the tertiary carbon. Then, an elimination reaction needs to take place to form an alkene intermediate, which will transpire through the E2 pathway with the tertbutoxide ion in tertbutanol. After this, an alcohol needs to be formed through hydroboration because we need the carbonyl group on the less subsituted carbon. After an alcohol is formed, the PCC reaction can oxidize the alcohol to make it a carbonyl. All these reactions are shown in choice C.

In the first step of the reaction, a chlorine is abstracted and a double bond is formed. In the ozonolysis step, the molecule is broken at the double bond and each carbon at that bond gets double bonded to an oxygen. The presence of zinc keeps it from becoming a carboxylic acid.

Working backwards, you must remove the oxygens from the final product and redraw the molecule at the double bond. This intermediate is 1,3-dimethylcyclopentene. Next, the chlorine must be added to one of the carbons on the double bond. The only possible choice is 2-chloro-1,3-dimethylcyclopentane.

In order to convert a secondary alcohol into a ketone, we must employ as a reagent.