Read the following context and choose the best option to answer the question.
Context: Hermia , Daisy and I had taken Pickering home to DUMBO and were on our way to Hermia 's house , a straight shot down Hicks Street . Police tape barred our entrance at Clark and the cop asked me for I.D. when I told him I lived here . I offered him plastic bags and Milk Bones and he let me pass with the warning I should n't come out again .
Question: Why did the police give them a warning ?
Options: 
A. They were investigating a crime at their home .
B. They had caught them doing something illegal .
C. They are n’t allowing people to enter the area .
D. They had caught them trespassing the area .


C