A. π2,4 (σ8='开发部'(EMP×DEP)) B. π2,4 (σ1=9(EMP σ2='开发部'(DEP))) C. π2,3 (EMP×σ2='开发部'(DEP)) D. π2,3 (π1,2,4,6(EMP) σ2='开发部'(DEP))