单选题
The information used by the computer to make its detailed maps ______. Ⅰ. was gathered by the Defense Department and the U. S. Geological Survey Ⅱ. shows points roughly 200 feet apart Ⅲ. involves altitude measurements
【正确答案】
D
【答案解析】第三段说the computer map的database包括altitude measurements，而这些资料又是由the Defense Department and the U.S．Geological Survey搜集的，后文又提到a grid of points 200 feet apart，选项D正确。