While hiking the Peralta Trail to Wheeler’s Needle and back, Rick spent 60% of his time walking uphill to Wheeler’s Needle and 40% of his time returning by the same trail. If he averaged 2 miles per hour uphill, what was his average speed for the round-trip?

A. 2 1/3 mph B. 2.25 mph C. 2.4 mph D. 2.5 mph E. 2.6 mph