Question

1. after his folding-wing prototype crashed, vuia

○ began making experimental helicopters.
○ started a factory to make engines for planes.
○ died in a crash while testing a friend’s plane.
○ moved to the west to buy a horse ranch.

Explanation:

After the crash of his folding-wing aircraft prototype, Romanian aviation pioneer Traian Vuia shifted his focus to developing experimental helicopters as part of his ongoing work in aviation innovation.

Answer:

began making experimental helicopters.