Question

what change, if any, should be made in sentence 3? (3) scientists have studied the migration for years, but them still do not fully understand how the butterflies find their way. change scientists to \we\ change \them\ to \they\ change \their way\ to \his or her way\ no change necessary

Explanation:

In the sentence, "them" is used as the subject of the clause "but them still do not fully understand...", but "them" is an object pronoun. The correct subject pronoun for the plural noun "scientists" is "they". Changing "scientists" to "we" is unnecessary and changes the meaning. Changing "their way" to "his or her way" is incorrect as "butterflies" is plural, so the possessive should also be plural. So the correct change is to replace "them" with "they".

Answer:

B. Change "them" to "they"