(;
GM[1]
SZ[19]
AW[dd][df][cn][dp][po][rn][qm][pm][on][nn][no][pb][nc][lc]
AB[fq][jp][pq][pn][qn][qo][ro][oo][op][np][qk][pf][pd][qc]
TR[no][nn][on][pm][qm][rn]
C[Problem 3. Black to play.  

White's marked stones in the lower right are vulnerable. How should Black attack them ? ]
(;B[ol]
TE[2]
C[Correct Answer.  

Peeping with Black 1 is severe. Next ... ]
;W[om]
C[... White must connect with 2. ]
;B[nl]
C[Black 3 is a vital point which prevents White from making shape in the center. ]
;W[ln]
C[After White jumps to 4, ... ]
;B[jn]
C[... Black attacks the whole white group with 5. ]
)
(;B[fo]
C[Failure.  

Locally, Black 1 is a strong move, but it only focuses on reinforcing Black's moyo at the bottom. ]
;W[ol]
C[White secures his stones by making shape with 2, and Black's attacking chance vanishes. <= ]
)
)