Chantal and Jean start hiking from a trailhead toward a fire tower. Jean is wearing a heavy backpack and walks slower. Chantal starts walking $4$ miles per hour. Halfway to the tower, the trail becomes really steep, and Chantal slows down to $2$ miles per hour. After reaching the tower, she immediately turns around and descends the steep part of the trail at $3$ miles per hour. She meets Jean at the halfway point. What was Jean\textquotesingle s average speed, in miles per hour, until they meet? (2021 AMC 10A Problems, Question \#6) 
选项为:A:$\frac{12}{13}$  B:$$1$$  C:$\frac{13}{12}$  D:$\frac{24}{13}$  E:$$2$$  请回答其中一个选项.