No. 6 Weekly problems

{"filetype":"problem","stonesize":"26",bounds:{'l':'0','t':'0','r':'11','b':'11'},"dummy":"dummy"}

(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[11]KM[0.00]
AW[bb][cc][cd][ae][ce][af][cf][bg]AB[cb][db][dc][dd][be][de][df][cg][bh][ch]LB[ba:A][ab:B][bd:C]C[Black to kill, A,B or C ?]
(;B[bd];W[bc];B[ba];W[ab];B[ad]C[Correct black is dead.])
(;B[ba];W[bd];B[ab];W[ac]C[Ko. not the best result])
(;B[ab];W[ba];B[bd];W[bc]C[White live with big territory]))