根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
For the first time in 10 years, the United States government has changed its guidance on how much exercise people need to stay healthy and when they should start.
For children and teens
The new guidance states that the most important time for children to begin exercising is between the ages of 3 and 5. That could be light activities, moderate activities, or even vigorous(剧烈的)activities.
Doctors say it is important to start young. They add that from birth to age 5, a child's brain develops more than at any other time in life. Also, children who start exercising at a young age are more likely to establish healthy behaviors they will continue into adulthood.
But that does not mean putting a small kid on a treadmill(跑步机)or other exercise equipment. After all, it's a kid's nature to play freely and happily.
But it shouldn't be less than one hour a day three times a week. Their activities should mostly be aerobic(有氧的)exercise, such as biking, swimming or running, which can strengthen the heart and lungs. Such exercise should also include muscle-and-bone-strengthening activities; such as climbing trees or playground equipment and playing sports.
For adults
For adults, the guidelines recommend exercising 150 minutes a week. That could be walking, gardening, dancing, etc. Experts say that even short amounts of aerobic exercise can provide health benefits, such as lowering blood pressure, reducing anxiety and improving sleep.
A. Any kind of activity that gets people exercising will do.
B. Aerobic activity works only if it lasts for at least 10 minutes.
C. Simply giving a kid the time and space to play actively is enough.
D. Children above 5 can have a relatively shorter time for daily exercise.
E. Children in this age range require about three hours 'active activities daily.
F. Attaining the health benefits from exercise may be harder than earlier thought.
G. These developments have a 1asting effect on a child's ability to succeed in life.