DrLittle Is Interested in Studying the Effects of a New

Dr.Little is interested in studying the effects of a new medication on children with asthma between the ages of six and 12.She gets permission to try the medication on asthma patients in several hospital clinics.In this example,the sample includes children

A) of all ages with asthma.
B) with asthma between the ages of 6 and 12.
C) with asthma between the of ages six and 12 from the clinics where Dr.Little does her study.
D) with asthma of all ages who do not receive medication.