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[ba][cb][dc]AB[da][bb][ac][bd][cd][dd]C[White to play - what's the best he can do?]PL[W]
(;W[ab]CR[ab]
(;B[aa]CR[aa]
;W[ca]CR[ca]
(;B[ab]CR[ab]
;W[cc]CR[cc]C[With his next move, White will capture with D3, securing a jigo. RIGHT CHOICE])
(;B[cc]CR[cc]
;W[ab]CR[ab]
;B[db]CR[db]
;W[bc]CR[bc]C[White wins - BC2 was a mistake]))
(;B[bc]CR[bc]
(;W[ca]CR[ca]
;B[aa]CR[aa]
;W[db]CR[db]
;B[ab]CR[ab]C[Seki & Jigo! RIGHT CHOICE])
(;W[db]CR[db]
;B[aa]CR[aa]
;W[ca]CR[ca]
;B[ab]CR[ab]C[Seki & jigo! RIGHT CHOICE])
(;W[cc]CR[cc]
;B[aa]CR[aa]C[Black wins!])))
(;W[cc]CR[cc]
;B[ca]CR[ca]
;W[db]CR[db]
;B[ca]CR[ca]C[Black wins])
(;W[ca]CR[ca]
;B[cc]CR[cc]
;W[ab]CR[ab]
;B[aa]CR[aa]C[Black wins]))