Which word shows the best meaning of the underlined word in this paragraph? 
 My grandparents are taking a trip for their fiftieth anniversary celebration. Part of it is a train excursion that is to last eight hours. That includes three hours for lunch and shopping. They are also taking a side expedition to a cave.
 A.
 journey
 B.
 passage
 C.
 tunnel
 D.
 exercise
 (the underline word is excursion)