Final answer:
Using the assumption of an average heart rate of 72 beats per minute and 1440 minutes in a day, an estimated 103,680 beats occur per day. Thus, none of the provided answer choices accurately reflect this estimate.
Step-by-step explanation:
To estimate the number of times the average person's heart beats in a day, let's use the average heart rate of 72 beats per minute as our assumption for calculation. Since there are 1440 minutes in a day (24 hours x 60 minutes), to find the daily heartbeats, we would multiply the number of minutes in a day by the average heart rate:
72 beats/minute x 1440 minutes/day = 103,680 beats/day
Therefore, the closest order of magnitude estimate from the given choices is A. 86,400, assuming an average person's heart beats once a second, although the actual estimated value is closer to 100,000 beats/day based on the calculation. Hence, none of the provided answer choices are correct based on our assumptions and calculations.