- D. Relax in the rest position. - A ??? ??? ??? Diarrhea is the most common recreational water illness because it is caused by dehydration. - False ??? ??? ??? When planning a water activity, it is best to include a friend or a group of friends rather than going alone, even if it is an easy activity. - True ??? ??? ??? It is not necessary to wear a lifejacket on a boat as long as there is one avail