The answer is source B because it has a listed author who is an expert and it is the governments organization website which are more reliable that a .com website. Source A does not even list the author so you do not know who wrote it could be anyone.
Get to bed earlier.Try to find out if there's a guy who likes her and have them get together. Theat'll really make her happy. Listen to quiet music when trying to sleep. It should most definitely help.
The heart rate is different while dancing, studying and riding a bike because the amount of blood needed for each activity is different. Blood pumps as fast as it as needed by the cells, which is why riding a bike has fast heart rate while studying has a regular heart rate.
