求助：XDF OLD BOOK 5-18

18. Radio interferometry is a technique for studying details of celestial objects that combines signals intercepted by widely spaced radio telescopes. This technique requires ultraprecise timing, exact knowledge of the locations of the telescopes, and sophisticated computer programs. The successful interferometric linking of an Earth-based radio telescope with a radio telescope on an orbiting satellite was therefore a significant technological accomplishment.

Which of the following can be correctly inferred from the statements above?

(A) Special care was taken in the launching of the satellite so that the calculations of its orbit would be facilitated.

(B) The signals received on the satellite are stronger than those received by a terrestrial telescope.

(C) The resolution of detail achieved by the satellite-Earth interferometer system is inferior to that achieved by exclusively terrestrial systems.

(D) The computer programs required for making use of the signals received by the satellite required a long time for development.

(E) The location of an orbiting satellite relative to locations on Earth can be well enough known for interferometric purposes.为什么选Ｅ，题目看不懂，请解释一下．谢谢．