49. Replacing a circuit breaker in a dark basement is one thing. __________
(1) It will perform many of the station's mundane tasks and reduce the number of death-defying spacewalks.
(2) But what if you had to climb around the outside of a spacecraft orbiting hundreds of miles above the Earth to do it?
(3) Fortunately, help is scheduled to arrive this month in the form of the Special Purpose Dexterous Manipulator, a versatile, \$200-million robotic handyman.
(4) This kind of dangerous maintenance work has become fairly common for astronauts aboard the International Space Station, where they spend as much time fixing the \$100-billion-plus orbiting science lab as they spend performing actual research.
(A) 2 4 3 1
(B) 4 1 2 3
(C) 3 2 1 4
(D) 2 3 1 4