The answer should be theme because it’s the storyline
The Sahara Desert begins at the Atlantic Ocean and extends to the Red Sea.
The dark is good the light is bad but they both can be good
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'.
