What is an enumerated power of congress ?

Article 1, Section 8 includes the listed powers that are vested to Congress, which are referred to as the Enumerated Powers. However, Congress also has implied powers that are set forth and implemented through the Necessary and Proper Clause of the Constitution, which is also found in Article 1, Section 8.

Explanation:

the graph shows the spread of railways in the 1800s.

based on the graph, the conclusion that can be drawn about germany is answer d)   by 1880, germany had more rail lines than great britain and russia.