Franco has the permission of George to walk across his yard on the way to school. If Franco brings twenty of his friends across the yard, and they stop to play ball:
a. Franco is not guilty of trespass to real property, because he had George's permission to cross the yard.
b. Franco's friends are not guilty of trespass to real property, because they were with Franco.
c. Franco is guilty of trespass to real property, because he walked across the yard.
d. Franco and his friends are guilty of trespass to real property, because they played ball in George's yard.