Answer:
The correct answer would be levodopa/carbidopa.
Tolcapone is a drug used as an adjunct to levodopa/carbidopa combination medication.
These drugs are used to treat the symptoms of Parkinson's disease.
Tolcapone is used to inhibit enzyme COMT (catechol-O-methyl transferase).
In the brain, levodopa is converted into dopamine which helps in controlling the movement.
Carbidopa helps in preventing the breakdown of levodopa in the blood which allows more levodopa to enter the brain. In addition, it helps in reducing the side-effects associated with levodopa such as vomiting, nausea et cetera.
Answer:
the limestone is the youngest, and therefore the top most rock layer found at the Grand canyon