For its Viking Program, NASA sent two probes to Mars on a journey to photograph the surface from orbit. Each probe also included a lander module that touched down on the surface of the planet in an effort to gather samples of Martian soil. The probe’s orbiter module remained in space as a communication relay and satellite. The Viking program was the most expensive NASA mission yet. The Viking 1 probe launched August 20, 1975, and Viking 2 launched September 9, 1975. The two probes survived for some time on the red planet, collecting data and transmitting back to Earth. The lander for Viking 1 lasting the longest before NASA shut it down in 1982.
The goals of the two orbiters were to carry the landers to Mars and obtain photographs of the planet from orbit. In order to carry out their tasks, the orbiter modules were large at over 6.5 ft (2 m) wide and 9.8 ft (3 m) tall. They both weighed over 5000 lbs (2300 kg) at launch. Eight solar panels and two nickel-cadmium batteries powered the orbiter modules.
The two landers were to land on the surface of the planet, photograph rock formations, and obtain soil samples. The landers also possessed other scientific sensors that would study other biological and chemical data as well as seismic activity, weather patterns, and magnetic fields of the planet. The landers were immobile once they touched down on the surface. Each was about the size of a small car and weighed about the same. Because the Viking Program took place before the digital age, NASA communicated with the probes via radios, and the probes stored all of their collected data on magnetic tape.
While the technology of these two probes seems primitive by today’s standards, the orbiters and launchers represented the pinnacle of modern technology at the time the Viking Program launched. The entire cost of the program was about one billion U. S. dollars.

Which of the following paragraphs best summarizes this news article?

W. The Viking Program sent two probes to Mars in the 1970s to study the surface of the planet. The orbiter modules photographed the planet from orbit while the lander modules touched down on the surface to take sample data.

X. The orbiter modules for the Viking Program were large and heavy, but the lander modules were smaller. The orbiters photographed the surface of the planet while the landers took soil samples.

Y. In 1975, NASA sent two landers to Mars to conduct surveys of the planet. The landers took soil samples and transmitted data back to earth. The Viking 1 lander shut down in 1983.

Z. The technology of the Viking Program probes was very modern at the time of their launch in 1975. NASA used radios to communicate with the two probes. The probes stored data on magnetic tape. Now, the technology is outdated.