What method of manufacturing, introduced in the early 1800s, made mass production possible? o the use of interchangeable partso the use of hand-crafted productsthe use of specialized laboro the use of expensive materials.
is the first one it or the third one lol

the use of interchangeable parts

Explanation:

With the creation of a mold for different products and having equal parts for different things the construction and fabrication of many products was easier and faster, this way mass production was possible.

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.