In the conversion shown below I need to find B . Initially I thought of protecting the carbonyl group using ethylene glycol and then carry out reduction of double bonds using hydrogenation but it is required to be a single reagent and cannot be multi step. What are the other ways in which it can be done?
You can do a normal hydrogenation reaction(H2,Pd) under low pressures as suggested by @Waylander. Alternatively you can use the Wilkinson's catalyst which also is a way to do catalytic hydrogenation but is capable of only reducing the double bond.