I still do n't know what was causing the massive failure because I saw no wrecked cars . I can only assume the cluster arose from several semi trucks all huddled together . Once we made it past that , we still had to drive to the exit and park .
What was causing the delay ?
Pick the best answer from the following options:
- A roadblock
 - A crash
 - A group of semi trucks
 - None of the above choices .


A group of semi trucks