<prompt> L-Dopa is combined with carbidopa in the treatment of parkinsonism to -Decrease the efficacy of levodopaDecrease the efficacy of levodopaIncrease the dose of levodopa requiredInhibit conversion of levodopa to dopamine in the CNS  <response>: Ans. is b i.e., Inhibit peripheral decarboxylation of levodopa Carbidopa is combined with levodopa to inhibit peripheral decarboxylation of levodopa and make more levodopa available to cross the blood brain barrier to reach its site of action. 