The correct option is D No change
While framing any sentence, the basic rule is - Subject + verb + object (if any). 'I' is the subject, 'drink' is the verb and 'glass of water' is the direct object. 'Every hour' is the adverb of time which expresses an exact number of times the action happens usually work best at the end of a sentence. Thus, according to the rule, the given sentence is correct so option D is the correct answer.