Choose the correct form of adverb for the given sentence:
I accepted the new task ______.

Willingly' is an adverb. The word 'willingly' shows that you are happy or pleased to do something.
E.g. People would willingly pay more for better services.
The given sentence implies that someone accepted the new task happily.
Hence, 'willingly' fits in the context.
According to the explanation and example that are given above, 'willingly' is the correct choice for the blank.
Complete Sentence - I accepted the new task willingly.