Given the task definition and input, reply with output. 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.

In the U.S., the music was being developed to create a more sophisticated sound,[citation needed] moving beyond just drum loops and short samples. In Chicago, Marshall Jefferson had formed the house group Ten City Byron Burke, Byron Stingily & Herb Lawson(from "intensity"). New Yorkbased performers such as Mateo & Matos and Blaze had slickly produced disco house tracks. In Detroit a proto-techno music sound began to emerge with the recordings of Juan Atkins, Derrick May and Kevin Saunderson.
what group did Marshall Jefferson form?