Teacher: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.
Teacher: Now, understand the problem? Solve this instance: Historical aspects of the Expo line route are noteworthy. It uses the right-of-way for the Santa Monica Air Line that provided electric-powered freight and passenger service between Los Angeles and Santa Monica beginning in the 1920s. Service was discontinued in 1953 but diesel-powered freight deliveries to warehouses along the route continued until March 11, 1988. The abandonment of the line spurred concerns within the community and the entire right-of-way was purchased from Southern Pacific by Los Angeles Metropolitan Transportation Authority. The line was built in 1875 as the steam-powered Los Angeles and Independence Railroad to bring mining ore to ships in Santa Monica harbor and as a passenger excursion train to the beach.
Student:
Beginning in what decade did the Santa Monica  Expo Air Line host freight and passenger services?