Read the sketch map of China's "five verticals and seven horizontals" national trunk highway, and answer questions 27-28 accordingly: The statement about the great significance of "five verticals and

Read the sketch map of China's "five verticals and seven horizontals" national trunk highway, and answer questions 27-28 accordingly: The statement about the great significance of "five verticals and seven horizontals" construction is correct. According to the geographical trend of the national highway, it is divided into three types: capital radial type, north-south vertical line type and east-west horizontal line type and numbered in turn. Capital Radiation consists of "1" and a two-digit routing number. For example, the national highway 10 1, that is, the Jingcheng-Shenyang line, is numbered clockwise, and the starting point of the national highway 103 must be Beijing, China.

So choose: a.