article: My friend,Dick,has a large police dog.Its name is Jack.Every Saturday afternoon,Dick takes Jack for a long walk in the park.Jack likes these long walks very much.
  One afternoon,a young man came to visit my friend.He stayed a long time.He talked and talked.Soon it was time for my friend to take Jack for a walk.But the man was still  there.Jack became very worried .He walked around the room several times and then sat down in front of the man and looked at him.But the man kept talking.Finally Jack couldn't _ it.He went out of the room and came back a few minutes later.He sat down again in front of the man,but this time he held the man's hat in his mouth.
question: Jack became very worried one afternoon because   _  .
options: Dick couldn't take him out for a walk at the usual time a young man came to visit Dick that afternoon Dick walked around his room several times he couldn't find the young man's hat