The correct answer is 'These flowers smell sweet'.The error lies in the usage of 'sweetly' instead of 'sweet'.Here we mean the smell of the flower and not what flower does. Thus, we need an adjective (sweet), not an adverb (sweetly) For example:- (1) That dress looks too short (not too shortly) for you. (2) The milk smells bad (not badly). Therefore, sweetly should be replaced by sweet.Hence, the correct answer is option 2. Correct Sentence: These flowers smell sweet.