(EEAr - 2014) nouns

The US space organization, NASA developed and built the first space shuttle. The shuttle was the first rocket to fly into space, come back to earth and fly again. The first shuttle to fly in space was Columbia. It took off  on the 12th April 1981. In January 1986 the shuttle Challenger exploded at take-off. Everyone on the shuttle died. This accident slowed down the shuttle programme for the next six years. A new shuttle, Endeavor, replaced Challenger in May 1992. 
On 25th April 1990, NASA used the shuttle Discovery to put the Hubble Space Telescope into space at a distance of 512 kilometres from the earth. Hubble travels around the earth and sends back photos of the stars and planets.

The nouns that correspond to the verbs in bold type, in the text, are, respectively: 
a) take off / explorer 
b) take-off / explode 
c) take off / exposure 
d) take-off / explosion
Alguém  pode me explicar porque o gabarito é  letra d sendo explosion e explode tem o mesmo significado portanto as duas estariam corretas
Gabarito : d

É simples!
Ele fala que o ônibus espacial decolou em 12 de abril de 1981. Decolou,em 1981= tempo passado. É um passado concluído. Decolar=take off. Passado? Decolou=Took off. Certinho.
A Challenger explodiu em janeiro de 1986. Explodiu em 1986,tempo passado. Concluído. Portanto,explodir=explode (verbo no infinitivo). Só que,explodiu no passado. Explodiu=explosion.

Muito obrigadoo pela ajuda