The president applauded Ms. Lawson, the chief of the marketing team, who worked incredibly _____ last month.
A) hard
B) harder
C) hardest
D) hardly
The given answer is A, but I wonder why "comparison" like B or "superlative" liek C can't be used here. We can say that he worked the hardest of his team or he worked harder than others, can't we? Please advise.
LCChang