(;AB[ab]AW[bc]AW[bd]AW[ad]AW[cc]AW[dc]AW[ea]AW[eb]AW[da]AB[fa]AB[fb]AB[fc]AB[ec]AB[dd]AB[cd]AB[be]AB[cf]AP[goproblems]
(;B[ba];W[bb];B[ca];W[db]C[CHOICE])
(;B[ca];W[db]
(;B[bb];W[cb];B[ba]C[RIGHT])
(;B[ba];W[bb];B[ae];W[ee]
(;B[ac];W[aa];B[ab];W[fe];B[cb];W[aa];B[ba];W[ca])
(;B[aa]C[seki, Black can kill the white group])))
(;B[bb];W[cb];B[ba];W[ac];B[ae]C[CHOICE])
(;B[cb];W[bb]
(;B[ba];W[db]C[CHOICE])
(;B[ca]
(;W[ba];B[db])
(;W[db]C[CHOICE];B[ae];W[ba]))))