{
  "correct_letter": "B",
  "correct_formula": "v = v_0 + g·t",
  "annotation": "Environment: g=-3.8, F_drag=0.0\nGround: e = 0.25\nBronzeAntiqueSphere: d = 2.0, e = 0.45, h = 15.0, v_0 = 0.0",
  "choices": [
    "F_fall = m·g·(1 + v/c) / √(1 - v²/c²)",
    "v = v_0 + g·t",
    "Q = m·c·ΔT",
    "P + (1/2)·ρ·v² + ρ·g·h = constant"
  ],
  "correct_index": 1,
  "physics_type": "FreeFall",
  "seed": "FreeFall|benchmark/freefall/8"
}