Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Space may be the final frontier, but it’s an expensive one to explore. There are ample problems with which to contend here on Earth, and that leads some people to wonder if space exploration is worth the hassle.

Humans did not evolve to go into space, but we go there anyway. That has led to the development of various technologies. Without space programs, we wouldn’t have GPS, accurate weather prediction, solar cells, or ultraviolet filters in sunglasses and cameras. There’s also medical research happening in space right now that could cure diseases and prolong human lives, and these experiments can’t be done on Earth. Space exploration could save your life.

Speaking of saving lives, space exploration could save all our lives. Our solar system has calmed down a lot since the early eons, but there are still uncountable big asteroids and comets out there that could smack into the planet. It’s happened several times in the past, each one causing a mass extinction. It’s not a matter of if another large asteroid hits Earth, but when. A robust space program is the only hope we have of deflecting such an object.

There are currently more than 7 billion humans, which is a lot. However, we’re all crammed together on this one planet. If something happened to Earth, our species could be wiped out. For example, the aforementioned asteroid impact. Colonizing other bodies in the solar system is a way to create a “backup” of humanity that will survive no matter what happens to Earth. Maybe future humans will be Martians who will never set foot on Earth.

As we develop new technologies on Earth, the strain on our natural resources continues to increase. The extraction of valuable minerals has led to a host of problems, including environmental damage and human exploitation, but there’s a wealth of precious materials in space. Startups like Planetary Resources want to mine asteroids instead of Earth, which would mean an effectively unlimited supply of raw materials that are rare on Earth.

There are more practical reasons for space exploration, but one of the principle reasons we must continue is that we’re explorers. That’s why humans number in the billions - from our earliest upright steps, we’ve endeavored to learn more about the world around us, and this allowed us to build civilization.

(Source: https://www.extremetech.com/)

The word “It” in paragraph 3 refers to _____.