[单选题]ZPW-2000A型无绝缘轨道电路中,室内发送断路器保险为（）A。
A.2
B.3
C.5
D.10

 Sally Ride was one of the first America’ s women astronauts. She became interested in the space program in 1962 when astronaut John Glenn orbited the earth in his Mercury space capsule. Sally was then ten years old at the time, but she remembered the launch and the landing as if they happened yesterday: She became a space fan. She quickly learned the name of every astronaut of the US (there were only eight of them in 1962), the date of every launch, and the name and number of every spacecraft. She could tell the speed of light ( 186,300 miles per second), the distance to the moon (238, 860 miles), and the names of the three nearest stars. By the time she was 16, Sally had decided to become an astrophysicist, a scientist who studies space. She finished higher education with a PHD in astrophysics from Stanford University.
The year 1965 saw the first time US hired scientist -- astronauts to conduct experiments on board Sky lab. Two years later, t
A. Sally Ride graduated from Stanford University in 1965.
B. The distance to the moon is 238,860 kilometers.
C. The speed of light is 186,300 miles per second.
D. There are only eight astronauts in the United States.