There is probably more grammatical "angst" over the choice of who and whom that any other pronoun selection. Who is, of course, nominative case, a case used only for subjects, while whom is objective case, a case used for direct objects, indirect objects, and objects of prepositions.
So, the easiest way to decide which of the two relative pronouns who/whom should be utilized is to go through the following steps:
- Locate the predicate [verb/verb phrase] of the clause in which the relative pronoun is to be placed. Then ask "Who is the doer of this action?" If there is no noun or pronoun that answers this question, then who is appropriate.
- If, however, there is already a noun or pronoun in place, then the objective case whom is necessary.
Now, back the the question under examination:
For the first choice of who/whom, who is used as an appositive to the subject of "Few drivers." The predicate is "get" and the drivers and its appositive who act as subjects.
For the second choice of who/whom, "pull" is the predicate. Asking "Who pulls?" gives the student the subject, "the police." Since "the police" is the subject, then whom must be used as the role of subject is already taken by "police."
I can see the difficulty of this sentence. First, the sentence is long and it contains two relative clauses. The key is to realize that relative clauses contain relative pronouns. These relative pronouns take its case from its function in the relative clause rather than the sentence. In other words, you have to ask yourself how the relative pronoun functions from a grammatical point of view within the relative clause. This is the key.
In this sentence, "who/whom get into their cars and drive at high speeds" is the first relative clause. Here the relative pronoun would have to be the subject. Hence, the answer is "who." The verb is "get into" and the object is "cars."
The second relative clause is: "who/whom the police pull out of the wrecks." Since the subject is "the police," the relative pronoun has to be the direct object. So, the answer is "whom."
'Whom' is an almost dead pronoun, only kept alive by grammarians. Don't stress about it.
Few drivers who get into their cars and drive at high speeds expect to be the ones who the police pull out of the wrecks.
This is the correct answer in modern English. 'Whom' is no longer needed. Tell your teacher that technically the answer to the second part of the sentence is 'whom', but language is an organic, living entity and it has evolved and 'who' is the modern, acceptable answer.