The correct option is
A Rauwolfia serpentinaRauwolfia serpentina or Indian snakeroot or sarpagandha, is a species of flowering plant in the family Apocynaceae.
Rauvolfia serpentina contains a number of bioactive chemicals, including yohimbine, reserpine, ajmaline, deserpidine, rescinnamine, serpentinine. A compound which it contains called as reserpine, was used in an attempt to treat high blood pressure and mental disorders including schizophrenia.
Atropa belladonna is commonly known as belladonna or deadly nightshade. It is a perennial herbaceous plant in the family Solanaceae. The foliage and berries are extremely toxic, containing tropane alkaloids. These toxins include scopolamine and hyoscyamine, which cause a bizarre delirium and hallucinations and are also used as pharmaceutical anticholinergics. The drug atropine is derived from the plant.
Colchicum luteum is beneficial for people suffering from swelling due to rheumatism.
Digitalis purpuria is used in modern medicine to increase the force of the systolic contractions.
Thus, the correct answer is option A.