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[cb][dc]AB[ca][ab][ac][cc][ad]C[White to play - what's the best he can do?]PL[W]
(;W[cd]CR[cd]
(;B[bc]CR[bc]
;W[ba]CR[ba]
;B[bb]CR[bb]
;W[da]CR[da]C[Seki, White wins by one point (the prisoner) RIGHT CHOICE])
(;B[bb]CR[bb]
;W[bc]CR[bc]
;B[bd]CR[bd]
(;W[cc]CR[cc]
;B[ba]CR[ba]C[Seki, White wins by one point (the prisoner) RIGHT CHOICE])
(;W[ba]CR[ba]
;B[cc]CR[cc]C[Black wins])))
(;W[bc]CR[bc]
;B[cd]CR[cd]
(;W[bb]CR[bb]
;B[ba]CR[ba]C[Seki & Jigo])
(;W[ba]CR[ba]
;B[bb]CR[bb]C[Black wins]))
(;W[bb]CR[bb]
;B[ba]CR[ba]
(;W[bc]CR[bc]
;B[cd]CR[cd]C[Seki & Jigo])
(;W[cd]CR[cd]
;B[bc]CR[bc]
;W[db]CR[db]C[Seki & Jigo]))
(;W[ba]CR[ba]
;B[bb]CR[bb]
;W[da]CR[da]
;B[cd]CR[cd]C[Black wins]))