(;SZ[9]AB[ch]AB[cg]AB[cf]AB[ce]AB[bf]AB[af]AB[bh]AB[ci]AB[dh]AB[dd]AB[dc]AB[eb]AB[ed]AB[fc]AB[fe]AB[ge]AB[gg]AB[gf]AB[hf]AB[if]AB[hh]AB[ih]AB[hi]AB[ii]AB[gi]AW[ah]AW[ag]AW[bi]AW[dg]AW[df]AW[de]AW[ee]AW[ef]AW[ff]AW[eh]AW[fh]AW[fg]AW[gh]AW[ei]AW[di]AW[cd]AW[bd]AW[be]AW[cc]AW[cb]AW[db]AW[hg]TR[bi]C[White has just taken the ko at the marked point. Where is black's best move?]AP[goproblems]
(;B[ec]C[RIGHT])
(;B[fd]C[RIGHT])
(;B[ai]C[NOTTHIS])
(;B[bg];W[ae])
(;B[ig];W[ae]
(;B[ai];W[fd]
(;B[bg];W[ec])
(;B[gd];W[bi]
(;B[fi];W[bg])
(;B[da];W[bg]))
(;B[ec];W[bi]
(;B[fi];W[bg])
(;B[da];W[bg])))
(;B[fi];W[bg]))
(;B[fi];W[ig]
(;B[hh];W[ae];B[ai];W[fd]
(;B[bg];W[ec])
(;B[gd];W[bi]
(;B[gi];W[bg])
(;B[da];W[bg]))
(;B[ec];W[bi]
(;B[gi];W[bg])
(;B[da];W[bg])))
(;B[ai];W[hh]C[(In fact white E9 is even better than H2, but this is already a failure for black.)]))
(;B[ae];W[ad];B[ai];W[fd]
(;B[bg];W[ec])
(;B[gd];W[bi]
(;B[da];W[bg])
(;B[ig];W[bg]))
(;B[ec];W[bi]
(;B[da];W[bg])
(;B[ig];W[bg])))
(;B[da];W[ae];B[ai];W[fd]
(;B[bg];W[ec])
(;B[gd];W[bi]
(;B[ca];W[bg])
(;B[ig];W[bg])))
(;B[ea];W[ae];B[ai];W[fd]
(;B[bg];W[ec])
(;B[gd];W[bi]
(;B[da];W[bg])
(;B[ig];W[bg]))
(;B[ec];W[bi]
(;B[da];W[bg])
(;B[ig];W[bg])))
(;B[gd]C[RIGHT]))