A scientist is conducting a study to determine how well a new medication treats ear infections. The scientist tells the participants to put 10 drops in their infected ear each day. After two weeks, all participants' ear infections had healed.
Which of the following changes to the design of this study would most improve the ability to test if the new medication effectively treats ear infections?
A. Have participants put ear drops in both their infected ear and healthy ear
B. Have participants use ear drops for only one week
C. Create a second group of participants with ear infections who use 15 drops a day
D. Create a second group of participants with ear infections who do not use any ear drops.
Many diseases have an incubation period. Which of the following best describes what an incubation period is?
A. The effect of a disease on babies
B. The period during which someone has an infection, but is not showing symptoms
C. The recovery period after being sick
D. The period during which someone builds up immunity to a disease