What is the main idea of the following passage?
The space program wanted to send a teacher into space along with the six astronauts. Thousands of people applied to become the first teacher in space. A high-school teacher from New Hampshire was selected. Her name was Christa McAuliffe. When asked about the upcoming, historic mission, McAuliffe replied, "I want to give an ordinary person's view of space." In 1986 the spacecraft, Challenger, exploded shortly after takeoff. Everyone aboard, including Christa McAuliffe, was killed.

A)Christa McAuliffe, the first teacher to be a part of a space mission, was killed in the Challenger explosion.
B) Christa McAuliffe joined a five-member crew.
C) Christa McAuliffe, a high-school teacher, was trained as an astronaut.
D In 1986 the spacecraft, Challenger, exploded shortly after takeoff.​