In my opinion it is letter d
, because in "I can see clearly now", clearly
is an adverb of manner, it is especifying the way the person sees sth. And also because of its positions, I mean, adverbs of manner are put after the direct object (or after the verb if there's no direct object).http://www.myenglishpages.com/site_php_ ... 5zW8pRdWSo
And in "You clearly have not understood what I just said", clearly
is a comment adverb. Comment and viewpoint adverbs add information about the speaker's opinion of events.
See the explanation: http://www.bbc.co.uk/worldservice/learn ... oint.shtml