The best writers make mistakes, but they rewrite to fix them. *
A. compound sentence
B. complex sentence
C. simple sentence
D. sentence fragment, incomplete sentence

i believe the answer is b. we

the correct answer is 4) infinitive phrase with a direct object

the explanation is that the infinitive phrase, "to with the younger children", functions as the object. it means the thing that the subject does.

1) no infinitive is incorrect because there is an infinitive verb in the sentence.

2) an infinitive only is incorrect because it is not in isollation. it is part of an infinitive phrase.

3) infinitive phrase with a subject is incorrect because in this example the infinitive phrase does not function as the subject doing the action of the sentence.

the answer would be " she kept on going till she got to the north."

good luck! hope i : )