Final answer:
The bird's rate per hour is 9.72 miles per hour.
Step-by-step explanation:
To calculate the rate per hour, we first need to find the total distance the bird travels in 90 days. Since it rests for 8 hours each day, it flies for 24-8=16 hours each day. Therefore, in 90 days, it flies for a total of 90 * 16 = 1440 hours. The total distance the bird travels is 14,000 miles, so the rate per hour is 14,000 / 1440 = 9.72 miles per hour. Therefore, the correct answer is not provided in the options given.