Directions: Choose the option that fills up the blank most correctly.

The Hubble Telescope should be ________ even if that means diverting the shuttle from other tasks and slowing plans to send astronauts to the Moon and Mars.

NASA's most important scientific instrument, the Hubble space telescope would begin to fail a few years from now, hence, this sentence emphasizes on its need to preserve this instrument. The clue comes from the word 'even', the clause that follows it provides an explanation to the blank. This implies that though tough tasks have to be undertaken, Hubble Telescope has to be preserved. Hence, (4) is the answer.