This answer is not correct. Remember that acidity increases due to electronegativity differences in a row (period) in the periodic table and acidity increases due to weaker bonds in a column (group) in the periodic table. In this question, you cannot make a direct comparison of all the compounds based on these theoretical reasons. You must compare those that are comparable...in the same group or in the same period. Perhaps reviewing questions 3 and 4 of this problem set will help you figure out this question.