Which would be considered a secondary source about the assassination of Abraham Lincoln? a diary entry by a witness to the assassination
an interview with a member of the audience at Ford’s Theater where Lincoln was shot
an interview with Booth’s understudy, who was not at Ford’s Theater the night of the assassination
a newspaper article written by a reporter who was in the audience at Ford’s Theatre

An interview with Booth's understudy

Explanation:

Secondary source is an article or paper talking about a thing, Without seeing it happen. For example, You have someone who saw Abraham Lincoln get shot. Then they write down what happened. The thing they wrote down is a primary source. Your friend tells you what happened in Ford's Theater, but he wasn't actually there. Thats a secondary source. Hope this helps, I spend 15 minutes typing this :)

the underground railroad (apocope of the metropolitan railroad) is a system of urban trains located within a city and its metropolitan area. it is characterized for being a massive transport of passengers in the big cities, uniting diverse zones and their environs, with high capacity and frequency and in segregated form to other systems of transport. metropolitan railroads are built underground or on the surface, although most systems use mixed models where sections are combined in both modalities.

1 - as a result, the metro tends to reduce car travel for two reasons: first, due to the greater transfer of users from the car and, second, due to the reduction in the acquisition of cars in homes located in sectors near the stations of the metro.

2 -the metro allows to contribute effectively to the achievement of all the objectives of an urban development policy: it improves the efficiency of the city's economy by reducing travel costs and also generates a higher level of activities in the city center, taking advantage of of the agglomeration economies.

3 -it is a clean means of transport, since it uses renewable energy (usually electricity), taking care of the environment and avoiding excessive pollution.