Answer:
Either B) increased parasympathetic stimulation of the heart. OR D) Constriction of elastic arteries to maintain blood pressure. I'm leaning more towards D) constriction of elastic arteries to maintain blood pressure.
Answer: D. Hypothesis B is more useful because it suggests a way to test the relationship between heart rate and caffeine intake.
Hypothesis A and B both are suggesting that caffeine intake is related to higher heart rate. But hypothesis B is proving it more certainly by suggesting the affects of caffeine intake on heart rate. As, heart rate of most people will be higher 30 minutes after they drink a cup of coffee is testifying the fact, that higher heart rate is related with caffeine intake.
Therefore, hypothesis B is more useful because it suggests a way to test the relationship between heart rate and caffeine intake.
Hi the answer to this isD.hope this helps.
