The correct answer is Option D.The question is about the total number of participants involved in the study mentioned in the given passage.The study involved both men and women. So when asked about the total number of participants we need to add the number of men and women.The number of participants is given in the sentence "Some 41,934 men... 84,276 women...". On addition of 41,934 and 84,276 we get 126,210.Thus Option D is correct.