Hiking is not only one of the best forms of physical exercise, but it is also one of the best forms of mental relaxation. It is good for all ages and especially good as a family and group activity.    Since there are so many different kinds of hiking, it is not possible to give any general rules to follow. Short and frequent hikes, needing no planning or special equipment, are enjoyed by most people.    *Keep in shape by walking at a fast pace for at least 15 minutes every day. Climbing stairs instead of using a lift and running not too far are also good ways of keeping in shape.    *On any hike nothing is more important than good, comfortable shoes.    *The things you take might include matches in a waterproof box, a knife, compass, map first aid items and flashlight.    *Cameras may be taken, but don't load with too much.    *On longer hikes keep a comfortable, steady pace and take rest stops often.    *Drink only safe water. If in doubt, boil the water.    *Don't go along the busy roads. When you have to use a road, keep as far over on the left as possible.    *Leave word at home or some other place as to where you are going and when you plan to return.    *On almost any hike, a map is a good idea. If going into a strange place, a detailed map is most useful.    *Take along a field guide on flowers, birds, rocks, or other subjects depending upon your interests. This can add greatly to the enjoyment and educational value of your hike. The author thinks that hiking is especially valuable for   _  .
single person families old people everyone
Question: Hiking is not only one of the best forms of physical exercise, but it is also one of the best forms of mental relaxation. It is good for all ages and especially good as a family and group activity.    Since there are so many different kinds of hiking, it is not possible to give any general rules to follow. Short and frequent hikes, needing no planning or special equipment, are enjoyed by most people.    *Keep in shape by walking at a fast pace for at least 15 minutes every day. Climbing stairs instead of using a lift and running not too far are also good ways of keeping in shape.    *On any hike nothing is more important than good, comfortable shoes.    *The things you take might include matches in a waterproof box, a knife, compass, map first aid items and flashlight.    *Cameras may be taken, but don't load with too much.    *On longer hikes keep a comfortable, steady pace and take rest stops often.    *Drink only safe water. If in doubt, boil the water.    *Don't go along the busy roads. When you have to use a road, keep as far over on the left as possible.    *Leave word at home or some other place as to where you are going and when you plan to return.    *On almost any hike, a map is a good idea. If going into a strange place, a detailed map is most useful.    *Take along a field guide on flowers, birds, rocks, or other subjects depending upon your interests. This can add greatly to the enjoyment and educational value of your hike. The author thinks that hiking is especially valuable for   _  .
A. single person
B. families
C. old people
D. everyone
Answer: