Runner A passed a post running at a constant speed of 50 miles per hour. Then, 15 minutes later, Runner B passed the same post at a constant speed of 60 miles per hour. If both runners maintained their speeds and both remained on the highway for at least 2 hours, how long after Runner B passed the gas station did he catch up with Runner A?	Choose the correct choice from the following answers
A) 30 min B) 45 min C) 1 hr D) 1 hr 15 min E) 1 hr 30 min
When Runner B is at the post, Runner A is 50/4 miles ahead on the highway. (the distance covered in 15 min)   every hour, Runner B runs 10miles more than Mary. how many hours will it takes him to run 50/4 miles more? the answer is (50/4)/10 = 25/20=1h15min.   Answer 1 hr 15 min
<result>D</result>
Runner A passed a post running at a constant speed of 50 miles per hour. Then, 15 minutes later, Runner B passed the same post at a constant speed of 60 miles per hour. If both runners maintained their speeds and both remained on the highway for at least 2 hours, how long after Runner B passed the gas station did he catch up with Runner A?