(;
GM[1]
SZ[19]
AW[qc][qd][qf][kc][ic][nc]
AB[pj][dj][dp][pd][pp][dd][jj][pc][oe][kd][gd][og]
TR[kc]
C[Problem 85. Black to play.  

White attaches with the marked stone, aiming to link up all her stones at the top. What should Black do next ? ]
(;B[jd]
TE[2]
C[Correct Answer.  

Black should extend to 1 and ... ]
;W[jc];B[id];W[hc]
C[... let White link up along the top with the sequence to 4. ]
;B[hd]
LB[ob:B][gc:A]
C[The moyo Black gets in the center after 5 far exceeds the profit White makes at the top. Next, Black A is big, much bigger than the territory White might make by playing White B. <= ]
)
(;B[md]
C[How the game continued.  

Black played 1, expecting White to defend her lone stone in the top right. but ... ]
;W[jd]
C[... White pushed with 2, ... ]
;B[ld];W[gb]
C[... then made a base for her stones by sliding to 4. ]
(;B[cg]
C[Instead of 5, ... <= ]
)
(;B[ec]
C[... Black should have played at 5 here, ... ]
;W[jf]
C[... forcing White 6, ... ]
;B[cg]
C[... then take the corner with 7. This would have been bigger. <= ]
))
)