Pedagogical studies suggest that for male teenagers from vulnerable populations, the most effective way for teachers to reach a student is
to interact with them individually and discover their needs before they become disengaged later in the semester.to interact with them individually and discover their needs before they become disengaged later in the semester
if they interact with them individually and discover their needs before the student has become disengaged later in the semester
to interact with each student individually and discover his needs before the student has become disengaged for the semester
for them to interact with them individually and discover their needs before they have become disengaged for the semester
if the teacher interacts with the student individually and discovers their needs before they have become disengaged for the semester
This sentence is using the pronoun they to refer to a singular noun: student. Changes need to be made to the pronouns them, their, and they to make them singular. As the sentence specifically says the study was only looking at male students, the pronouns need to be singular and masculine. Choices A, B and D ignore this problem completely, and Choice E fixes the problem partially, but still leaves the incorrect they in the latter half of the answer. Also, the linking verb is connects an infinitive, to reach, with a list of other infinitives serving the same function, to interact and to discover. All three need parallel construction. To interact and discover form a list and must be parallel to each other. The preposition to is understood and thus isn't repeated before discover. Both infinitives must be parallel to the earlier infinitive to reach, since they are logically listed as ways to reach a student. Choice C is the correct answer