(;AW[sb]AW[rb]AW[qc]AW[pc]AW[ob]AB[nb]AB[nc]AB[od]AB[pd]AB[qd]AB[rd]AB[rc]AB[qa]TR[qa]C[black has just played the marked stones what has white to do?]AP[goproblems]
(;W[ra];B[oa]
(;W[pa];B[pb]
(;W[oc];B[qb])
(;W[qb];B[oc];W[pa];B[ob]))
(;W[qb];B[pa];W[pb];B[na]))
(;W[pa];B[qb];W[ra];B[sc];W[pb]C[RIGHT])
(;W[oa];B[qb]
(;W[pb];B[ra])
(;W[ra];B[sc])
(;W[pa];B[ra]))
(;W[pb];B[pa]
(;W[oa];B[ra])
(;W[ra];B[oa]))
(;W[qb];B[pa]
(;W[oa];B[ra])
(;W[ra];B[oa];W[pb];B[na])))