A. permanent
B. beneficial
C. parochial
D. dangerous
pernicious : having a harmful effect, especially in a gradual or subtle way.
permanent : lasting or intended to last or remain unchanged indefinitely.
beneficial : resulting in good; favourable or advantageous.
parochial : having a limited or narrow outlook or scope.
dangerous : able or likely to cause harm or injury.
Antonym of pernicious is beneficial
