Explanation: In indirect speech, when converting a present tense statement made in the past into reported speech, the reporting verb ("said" in this case) remains in the past tense, but the tense of the verb in the reported speech can either remain the same if the statement is still true or change accordingly. In this sentence, the original statement is in present tense ("I clean my teeth twice a day"). So, when reporting it, the tense of the verb "clean" doesn't need to change. Hence, the correct option is B, where the reported speech maintains the present tense: "He said that he cleans his teeth twice a day."