whiCh oF thE Following ConDition is lEAst likEly to BE thE oBstAClE to thE EFFiCiEnt AlloCAtion oF proDuCtivE rEsourCEs:
A．

A. priCE Controls

B．

B. tAxEs AnD trADE rEstriCtions

C．

C. pErFECt CompEtition