<u>Answer:</u>
Stop [!] the train is approaching.
<u>Explanation:</u>
The punctuation should be an exclamation point because it used at the end of a sentence or a short phrase which expresses very strong feeling.
<em>Hoped this helped.</em>
The answer is C because there is only a dependent clause.
This practice is divisive, it is unfair, it is archaic.
hope this helps :)