Reading Comprehension

The question of the existence of liquid water on the surface of Mars has fascinated scientists for over three centuries, with new information repeatedly shedding new light on the subject. Other than the significance of water in the geological research of Mars and its relevance to the study of the solar system as a whole, the existence of water also sparked the imagination of many in regards to the possibility of life on the Red Planet. Such speculations arose from the assumption that a planet's capability to develop and sustain life is highly dependent on the prevalence of liquid water on its surface.

Originally, scientists speculated that Mars may have liquid water on its surface. The basis for this theory was changes in light and dark areas in the polar regions seen even by the most primitive telescopes, which were attributed to seas and continents. Furthermore, long dark lines visible across the surface were suggested by certain scientists to be irrigation channels, carrying liquid water. However, the dark features were consequently proven to be optical illusions, and after the first flyby of the Mariner 4 spacecraft in 1965, new data was discovered that discredited such assumptions.

Information gathered by spacecrafts at the end of the 20th century and during the early years of the 21st century indicated that although liquid water was previously present on Mars' surface, it cannot exist there today due to Mars' low atmospheric pressure and distance from the sun. This information was collected by a group of orbiting spacecrafts, adjoined by telescopic observation of the planet from space and several landers and rovers which explored the planet's surface. These data brought scientists to believe Mars was previously largely covered in water, with geyser-like eruptions occurring even up to recent years.

Still, the debate over liquid water on Mars is far from being resolved and is continually fueled by new evidence. Currently, two rovers - Spirit and Opportunity - continue to explore the surface and broadcast information back to earth. In June 2007, an image from Mars of blue patches resembling water puddles was published by NASA; however, speculations were soon dismissed as the picture taken was of a sloped wall of a crater. Despite such disappointments, some scientists still argue that as long as conclusive evidence regarding the nonexistence of liquid water on Mars is not found, the search must go on.




Which of the following statements would provide the most logical continuation of the final paragraph of the passage?

Scientists today look back to the scholars of medieval times, who were sadly fooled by optical illusions.

In this spirit, NASA has begun preliminary work on the first manned mission which may allow mankind to examine Mars first hand for signs of liquid water.

Needless to say, Mars enthusiasts were outraged that such a small detail was overlooked.

Although Mars seems to have been previously covered in water, it is hard to believe that liquid water will be found on it, so funds may be put to better use in other areas of space science.

Even if liquid water is found on the Red Planet, it does not necessarily mean there has ever been life on it.

B is the closest possible. "Currently, two rovers - Spirit and Opportunity - continue to explore the surface and broadcast information back to earth" but it does not mention when the work started so it may or may not be preliminary work. Can anyone shed light on this?