Secondary school students achieve broad mastery of the curriculum if they are taught with methods appropriate to their learning styles and they devote significant effort to their studies. Thus, if such broad mastery is not achieved by the students in a particular secondary school, those students are not being taught with methods appropriate to their learning styles. The conclusion can be properly drawn if which one of the following is assumed? ['Secondary school students who devote significant effort to their studies do not always achieve broad mastery of the curriculum.', 'Even if secondary school students are taught with methods appropriate to their learning styles, they will not achieve broad mastery of the curriculum if they do not devote significant effort to their studies.', 'Secondary school students do not achieve broad mastery of the curriculum if they are not taught with methods appropriate to their learning styles.', 'As long as secondary school students are taught with methods appropriate to their learning styles, they will devote significant effort to their studies.']