In the weak form of the principle of virtual displacements, 0=\(\int_{V_e}\)(σijδεij+ρüiδui)dV-\(\int_{V_e}\)fiδuidV-∮set̂iδuids , applied to plane finite elastic element,which term corresponds to virtual strain energy stored in the body?

(a) \(\int_{V_e}\)(σijδεij)dV

(b) ∮set̂ iδuids

(c) \(\int_{V_e}\)(ρü iδui)dV

(d) \(\int_{V_e}\)fiδuidV

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The above asked question is from Plane Elasticity topic in division Plane Elasticity of Finite Element Method