How is a person's behavior affected by being part of a group? How are the townspeople in "The Lottery" similar to the people on the subway platform? How are they different?

1. in which sentence is the underlined portion a predicate nominative? for astronauts, going into space to repair orbiting equipment becomes a challenge. for astronauts, going into space to repair orbiting equipment becomes tricky. for astronauts, going into space to repair orbiting equipment becomes challenging. for astronauts, going into space to repair orbiting equipment becomes frequent.