题目选项分析

With air traffic routes over the North Pole currently used by only two or three planes a day, opening those routes to thousands more commercial planes a year has been found by a joint Canadian-Russian study as both feasible and desirable.

Although air traffic routes over the North Pole are currently used by only two or three planes a day, a joint Canadian-Russian study has found that opening those routes to thousands more commercial planes a year is both feasible and desirable.