Parkinson's disease is a neurodegenerative disorder. The most effective treatment for parkinson's disease is a combination of Levodopa and Carbidopa. Which statement is correct about this treatment: a. Dopamine can cross the blood brain barrier b. The best results of levodopa treatment are obtained in the first few days of treatment c. L-DOPA is Used because dopamine cannot cross the blood brain barrier. d. Carbidopa normally added to L-DOPA to reduce the Central conversion of L-DOPA to dopamine. e. L-DOPA exerts its effect by Decrease cholinergic activity