Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 35 to 42

GETTING CURIOUS ABOUT CURIOSITY'S MISSION TO MARS

The topic of space exploration reached a high point during the 1960s, as Soviets and Americans competed for dominance. Yet after the Soviets put the first man in space and Americans landed the first men on the moon, many people lost interest as nothing else could compare to these groundbreaking accomplishments. Recently, a robotic rover on a mission to Mars has generated massive interest the public.

Curiosity is a robotic car-sized rover that is part of NASA's long-term plan to learn more about the terrain and conditions on the Red Planet. One of its main goals was to determine whether or not it was possible for life to develop on Mars. Using mechanical arms, Curiosity can gather soil and rock samples from the ground and analyze them to determine their chemical composition. Since transporting around Mars was vital to the success of the mission, a lot of effort was put into Curiosity's transportation abilities. Mars' terrain is not smooth, so designers enabled Curiosity to roll over bumpy areas. Once Curiosity left the Earth, there would be no opportunities to repair it, so engineers also had to be spot on about Curiosity's power solution. Therefore, they devised a system that can generate power internally from a radioisotope generator. Finally, to capture stunning pictures of Mars, Curiosity was equipped with several state-of-the art cameras. The cameras also help the rover avoid hazards, navigate, and detect information about the atmosphere.

After a 350-million-mile journey, Curiosity landed on Mars in 2012, an impressive 1.5 miles away from its initial target. Upon arrival, NASA's website crashed due to an overload of visitors. People just couldn't seem to get enough information on the mission. But the real thrills came in the weeks and months that followed, as people got their first real glimpse about what life was really like on Mars. The mission was originally supposed to last for two years, but scientists are now optimistic that it could continue for up to 15 years, depending on Curiosity's condition. No matter what happens at this point, it is safe to say that Curiosity's mission to Mars has been a smashing success.

According to the passage, the popularity of space exploration reached its___________ in the 1960s.

What best matches the meaning of the phrase "spot on" in paragraph 2?