10 points 4.During a recent bike ride, the chain on Elena's bicycle slipped off the rear gear. In order to re-attach the chain, she turned her bicycle upside- down and placed the loose chain on top of the rear gear. She used the pedal to slowly rotate the tire 3/8 of one complete rotation to reattach the chain, as shown by the arrow in the following figure. What is the measure of the central angle? * O 45 degrees 67.5 degrees O 120 degrees O 135 degrees