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[ca][ab][bb]AB[db][cc][dc][bd]C[White to play - what's the best he can do?]PL[W]
(;W[bc]CR[bc]
(;B[cd]CR[cd]
;W[cb]CR[cb]
;B[ba]CR[ba]
(;W[aa]CR[aa]C[White wins by one point (the prisoner). RIGHT])
(;W[ac]CR[ac]C[NOTTHIS])
(;W[da]CR[da]C[NOTTHIS]))
(;B[cb]CR[cb]
;W[cd]CR[cd]
;B[ba]CR[ba]
;W[ad]CR[ad]
;B[da]CR[da]
;W[aa]CR[aa]C['One eye beats no eye' - Black is lost.]))
(;W[cb]CR[cb]
;B[bc]CR[bc]
;W[ac]CR[ac]C[Seki & jigo - White can do better.]))