Which of the following approaches to cost is the least transparent?

Price acceptance is the least transparent approach because the buyer simply accepts the supplier’s quoted price without investigating its basis or fairness. There is no visibility into the supplier’s cost structure, margins, or pricing methodology.

By contrast:

Price management involves actively managing pricing discussions.

Cost down involves collaborative efforts to reduce costs after production.

Cost out involves eliminating costs before production through design.

[Ref: CIPS L5M6 Study Guide, p.81 – Costing methods]