Instructions: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Input: The Eritrean highway system is named according to the road classification. The three levels of classification are: primary (P), secondary (S), and tertiary (T). The lowest level road is tertiary and serves local interests. Typically they are improved earth roads which are occasionally paved. During the wet seasons these roads typically become impassable. The next higher level road is a secondary road and typically is a single-layered asphalt road that connects district capitals together and those to the regional capitals. Roads that are considered primary roads are those that are fully asphalted (throughout their entire length) and in general they carry traffic between all the major towns in Eritrea.
Output:
How is the Eritrean highway system named?