Answer:
I had this same question and got a 100% on this assignment after using the answer above! The answer above is correct!
It is 3.) because if you use process of elimination than you should be able to immediately cross out 1. and 2. because medicines are measured very accurate and have to pass a lot of tests to make sure that they are safe. Than 4. is also a good answer but it isn't the best because than she wont be able to relive her headache. That's why 3. is the best option.