One is: How did jim and huck change? One way is by getting closer
It should be moved to the beginning of the sentence, that means, that it should be placed before "The motorcycles raced" (option A).
Explanation: "down the track" is a prepositional phrase. All prepositional phrases have no verbs nor subjects. These can be used as adjectives or adverbs. They can be placed either after the verb and at the begining of a sentence. When placed at the beginning of a sentence, it sounds more formal than the common structure composed of 'subject + verb + predicate' and this construction has to be followed by a comma.
In this case, the answer would be:
'Down the track, the motorcycles raced for the prize'.
Child bearer is another term for a mother. Like "birth giver" "mother" ect.
Yes, you can use it in a sentence.
"She is adopted but the kind woman in the red dress is the child bearer."
"Susan is a child bearer of the sweet little girl."
I have no idea if these are even good examples, but it is a strange phrase anyways, I hope I helped.