question: You are answering a 3D spatial-reasoning question from a SINGLE monocular driving image with numbered bounding boxes. Frontier models routinely get these right by luck while reasoning incorrectly: they lean on flat-image shortcuts ('lower in the frame = closer', 'bigger box = nearer', 'left in the image = to my left') that collapse on elevated roads, slopes, curves, and intersections. To answer reliably you must reconstruct the real 3D scene, not the pixel layout. Reason explicitly and quantitatively.
  
  Question: Among all labeled objects, which one is furthest ahead of us along our forward driving axis?
  
  Reasoning protocol (metric 3D):
  1. For each candidate object, estimate its position as (forward distance along the ego heading, lateral offset) in meters.
  2. The question concerns the FORWARD axis specifically: project each object onto the ego's direction of travel. An object that is close in straight-line distance but far to the side has a SMALLER forward projection; account for this rather than using absolute distance or image position.
  3. Compare the forward projections and select accordingly.
  
  Finish with a single line in the exact format: 'Answer: <LETTER>'.
choices: A. <1> B. <4> C. <3> D. <6>