A) The author argues that the reasoning behind space colonization in the 1950s
was optimism, whereas now the motivation comes from distress and fear of the
future.
B) The author argues that the 1950s attitude towards space colonization was
motivated by competition in the space race, but it is now prompted by ambition
and greed.
C) The author argues that the 1950s attitude towards space colonization was naive
and unrealistic, whereas now it is pessimistic and desperate.
D) The author argues that the reasoning behind space colonization in the 1950s
was hope in the future, whereas now the motivation comes from a desire to
return to the past.