[en] It is becoming crucial to understand orbital-angular-momentum contributions for clarifying the nucleon-spin issue in the parton level. Twist-two structure functions b₁ and b₂ for spin-one hadrons could probe orbital-angular-momentum effects, which reflect a different aspect from current studies for the spin-1/2 nucleon. The structure functions b₁ and b₂ are described by tensor-polarized quark and antiquark distributions δ_Tq and δ_Tq. Using HERMES data on the b₁ structure function for the deuteron, we made an analysis of extracting the distributions δ_Tq and δ_Tq in a simple x-dependent functional form. Optimum distributions are proposed for the tensor-polarized valence and antiquark distribution functions from the analysis. A finite tensor polarization is obtained for antiquarks if we impose a constraint that the first moments of tensor-polarized valence-quark distributions vanish.