Answer:
A : more accidents have not already occur
Step-by-step explanation:
The narrator tells of what a terrible experience it is for children who have to walk along the road with cars speeding by at an alarming rate. He mentioned that it was a thing of luck that more accidents have not already occurred.
Sidewalks are meant to be a safer route for passersby. Since the students are at the mercy of cars speeding along in Green Street, that would only mean that there is an absence of sidewalks to protect them.