Not many points to choose from :) There are two equally interesting variations, so maybe you should try "navigate soltution" after solving the problem.
Please find Blacks best result!
(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[ab][bb][dc][dd]AB[db][ac][ad][bd]C[Black to play - what's the best he can do?]PL[B]
(;B[cb]CR[cb]
(;W[cc]CR[cc]
;B[bc]CR[bc]
;W[cd]CR[cd]
;B[bc]CR[bc]C[Black wins! RIGHT CHOICE])
(;W[bc]CR[bc]
;B[cc]CR[cc]
;W[cd]CR[cd]
;B[bd]CR[bd]
;W[ca]CR[ca]
;B[ba]CR[ba]C['One eye beats no eye' - Black wins! RIGHT CHOICE]))
(;B[cc]CR[cc]
(;W[cb]CR[cb]
;B[cd]CR[cd]
;W[dc]CR[dc]C[White wins!])
(;W[bc]CR[bc]C[This is wrong for White....]
(;B[cb]CR[cb]C[This leads back to the solution...]
;W[cd]CR[cd]
;B[bd]CR[bd]
;W[ca]CR[ca]
;B[ba]CR[ba]C[Black wins :)])
(;B[cd]CR[cd]C[This move is also possible, of course]
(;W[cb]CR[cb]
;B[dc]CR[dc]
;W[ca]CR[ca]
;B[ba]CR[ba]
;W[aa]CR[aa]C[Seki, Black wins by one point (2 prisoners against 1).])
(;W[dc]CR[dc]
;B[cb]CR[cb]C[Black wins.])))))