(;AW[ca]AW[cb]AW[db]AW[eb]AW[gb]AW[ga]AW[hb]AW[hc]AB[ba]AB[bb]AB[cc]AB[dc]AB[bd]AB[ec]AB[gc]AB[gd]AB[fd]AB[fb]TR[fb]C[Black played the triangle stone. Connect white in the best way possible.]AP[goproblems]
(;W[ea]LB[fc:K]LB[fa:D]C[Black can't play D; K is a ko threat.RIGHT])
(;W[fa];B[ea]
(;W[fc]C[Ko])
(;W[da];B[ea]))
(;W[da];B[ea]))