Eric Foreman was one of House’s original diagnostic-team members introduced in the House M.D. pilot.
Foreman is a neurologist recruited by Gregory House to work in the Department of Diagnostic Medicine. Alongside Robert Chase and Allison Cameron, he forms the core team seen during the first season. The three doctors bring different specialties and personalities to House’s difficult cases.
The wording refers to the pilot-era team rather than the first person ever shown working with House. Robert Chase and Allison Cameron were also members of that original team, so a question asking for any original team member would allow several correct answers. Foreman is the single answer here because he is identified by his neurology background and later leadership role.
Omar Epps portrayed Foreman throughout the series. Foreman eventually became a department leader and, by the final episode, a senior authority at Princeton-Plainsboro.