Some researchers have suggested that our 24-hour sleep/wake cycle may partially be a response to a world where the sun rises and sets on a 24-hour cycle. Imagine that the earth is gradually speeding up, and in 10,000 years the sun rises and sets on a 22-hour cycle instead. If you came to this future world you might expect that people would tend to

a. show no consistent wake-sleep cycle
b. follow the old cycle and still fall asleep once every 24 hours
c. develop an even longer 26- hour sleep/wake cycle
d. follow the shortened cycle set by the sun and fall asleep once every 22 hours