(;
GM[1]
SZ[19]
AW[dd][df][dp][qo][po][om][pl][ql][nc]
AB[ck][pq][qp][mq][qm][pj][pd][fc][jd]
LB[lc:A][oc:B][pf:C]
C[Problem 121. Black to play.  

How should Black attack the lone white stone in the upper right: at A, B, or C ? ]
(;B[oc]
TE[2]
C[Correct Answer.  

Black 1 is a basic attacking move in this kind of position. ]
;W[nd]
C[When White stands to 2, ... ]
;B[pf]
C[... Black jumps to 3. White's stones are now heavy and no matter how she defends, they will come under attack. <= ]
)
(;B[pf]
C[Failure.  

If Black plays 1 here, ... ]
;W[pb]
C[... White will slide to 2 and secure her stone. <= ]
)
(;B[lc]
LB[qc:A]
C[Failure.  

Against the pincer of Black 1, White will not invade at A. ]
;W[pf]
C[Instead, she will play 2 ... ]
;B[nd];W[ph]
C[... and 4, attacking the black stone in the middle of the right side. <= ]
)
)