Read the following context and choose the best option to answer the question.
Context: 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 .
Question: What was causing the delay ?
Options: 
A. A roadblock
B. A crash
C. A group of semi trucks
D. None of the above choices .


C