Why is the Sinoatrial (SA) node so important in the electrical activity of the heart?

Darren was recently ticketed for speeding over 110 mph on the freeway. when the police officer stopped darren and asked him why he was going so fast, he replied that he was "king of the world." the month before this, darren felt sad and listless and had trouble getting up the energy to go to school. he probably suffers from:

Alcohol is used in over the counter medications because it is a solvent and can more thoroughly dissolve the solid ingredients of the medication. true or flase.

Which of these is likely to be the best source of valid health information?