Which is the 1st systemic fungicide?

Answer: Option D

Carboxin is the 1^st systemic fungicide.
Carboxin is an anilide obtained by formal condensation of the amino group of aniline with the carboxy group of 2-methyl-5, 6-dihydro-1, 4-oxathiine-3-carboxylic acid.
A fungicide for control of bunts and smuts normally is used for the treatment of seed. It has a role as a succinate dehydrogenase inhibitor and an antifungal agrochemical.
It is an anilide, an enamide, an oxacycle, an organosulfur heterocyclic compound, an anilide fungicide and a secondary carboxamide.