Question

What is the meaning of the word, unprecedented, as used below?

It was then that the Society for the Extinction of the Slave Trade and the Civilization of Africa, headed by Prince Albert, the husband of Queen Victoria, launched an unprecedented attempt to eradicate slavery at its origin. The ambitious plan was to win or buy the cooperation of the tribal chieftains along the River Niger through a series of treaties, as well as introduce Christianity and increase commerce
A) Unremarkable
B) Repeated
Eliminate
C) First-Time
D) Odd

Answer 1

I think the answer is all

Answer 2

the answer is c

un·prec·e·dent·edˌənˈpresədən(t)əd/adjectivenever done or known before."the government took the unprecedented step of releasing confidential correspondence"synonyms:unheard of, unknown, new, novel, groundbreaking, revolutionary, pioneering, epoch-making; unparalleled, unequaled, unmatched, unrivaled, without parallel, without equal, out of the ordinary, unusual, exceptional, singular, unique; formalunexampled"warfare on an unprecedented scale"