(;
GM[1]
SZ[19]
AW[cd][dc][ec][cf][qf][qg][ph][oh][qi][ri][rj]
AB[dp][pd][pp][fc][fd][ed][jd][nd][qh][pi][pj][qj][rk]
TR[qg]
C[Problem 153. Black to play.  

Where should Black play after White secures her position in the upper right with the marked stone ? ]
(;B[jp]
LB[qk:A]
TR[pi][pj][qj]

TE[2]
C[Correct Answer.  

The marked stones on the right side are heavy, so Black should take a bit point at the bottom with 1. This move even has the effect of defending the cut at A by making a ladder-blocking move at the bottom more difficult for White. Regardless, Black should be flexible enough to sacrifice the marked stones should that become necessary. The white stones above are settled, so Black has no prospects for attack by saving these stones. <= ]
)
(;B[ql]
C[How the game continued.  

Black made shape with 1, but ... ]
;W[jq]
C[... this gave White the chance to break up the bottom with 2. ]
;B[gq]
C[After Black made the checking extension of 3, ... ]
;W[qq]
C[... White took the corner with the sequence from 4 ... ]
;B[pq];W[qp];B[qr];W[rr];B[pr];W[qn]
C[... to 10. The game was becoming difficult for Black. <= ]
)
)