{
  "correct_letter": "A",
  "correct_formula": "ΣF_ext = 0",
  "annotation": "Environment: g=-9.81, F_drag=0.0",
  "choices": [
    "ΣF_ext = 0",
    "τ_net = Σ(F_i·r_i·sinθ_i) · e^(-μ·t)",
    "T = 2π·√(m/k)",
    "G = m·g"
  ],
  "correct_index": 0,
  "physics_type": "AtRest",
  "seed": "AtRest|benchmark/at_rest/7"
}