First Principles Thinking: core idea
C is correct. Cost leadership is executed through scale economies, favorable input access, strict cost control, aggressive pricing, low-cost distribution, and scope economies -> apply those features -> conclude that the strategy is cost leadership.
Option A is wrong because differentiation relies on uniqueness, brand, service, quality, and premium pricing.
Option B is wrong because focus targets a particular customer group, product, or geography rather than broad low-cost scale alone.