Is this a "C" or a "c"? It's a "C"! The solution will show why...
Please find the best result for White!
(japanese rules)
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[4]KM[0.00]
PW[Weiß]PB[Schwarz]AW[bd][cd]AB[ba][ca][ab][ac]C[White to play - what's the best he can do?]PL[W]
(;W[cb]CR[cb]
(;B[db]CR[db]
(;W[bb]CR[bb]
;B[cc]CR[cc]
;W[bc]CR[bc]
;B[dc]CR[dc]C[Seki & jigo. The white stones make a 'c' now :) RIGHT])
(;W[dc]CR[dc]
;B[bb]CR[bb]
(;W[da]CR[da]
;B[bc]CR[bc]
(;W[cc]CR[cc]
;B[db]CR[db]C[With his next move, Black connects the ko: Seki & jigo (one prisoner each). RIGHT])
(;W[db]CR[db]
;B[cc]CR[cc]C[Black wins.]))
(;W[cc]CR[cc]
;B[da]CR[da]C[Seki & jigo. RIGHT]))
(;W[cc]CR[cc]
(;B[dc]CR[dc]
;W[bb]CR[bb]C[Seki & jigo! RIGHT])
(;B[bb]CR[bb]
;W[dc]CR[dc]
;B[da]CR[da]C[Seki & jigo!])))
(;B[bb]CR[bb]
(;W[db]CR[db]
;B[bc]CR[bc]
;W[cc]CR[cc]
;B[dc]CR[dc]C[Now, please capture :)]
;W[dd]CR[dd]C[Seki, White wins by one point (the prisoner)])
(;W[cc]CR[cc]
;B[db]CR[db]
;W[dc]CR[dc]
;B[da]CR[da]C[Seki & jigo.]))
(;B[bc]CR[bc]
;W[cc]CR[cc]
(;B[db]CR[db]
(;W[dc]CR[dc]
(;B[bb]CR[bb]
;W[da]CR[da]C[With his next move, White connects the ko: Seki, White wins by one point (the prisoner).])
(;B[da]CR[da]
;W[bb]CR[bb]C[White wins.]))
(;W[bb]CR[bb]
;B[dc]CR[dc]C[Seki & jigo.]))
(;B[bb]CR[bb]
;W[db]CR[db]
;B[dc]CR[dc]C[Now, please capture :)]
;W[dd]CR[dd]C[Seki, White wins by one point (the prisoner)])))
(;W[cc]CR[cc]
;B[cb]CR[cb]
;W[bc]CR[bc]
;B[db]CR[db]
;W[bb]CR[bb]
;B[dc]CR[dc]C[Black wins.])
(;W[bc]CR[bc]
;B[cb]CR[cb]
(;W[bb]CR[bb]
;B[cc]CR[cc]C[Black wins.])
(;W[dc]CR[dc]
;B[cc]CR[cc]
(;W[db]CR[db]
;B[bb]CR[bb]C[Black wins.])
(;W[bb]CR[bb]
;B[db]CR[db]C[Black wins.])))
(;W[dc]CR[dc]
;B[bc]CR[bc]
;W[cb]CR[cb]
;B[cc]CR[cc]C[Black wins.]))