EVENT
BOARDSIZE 19
SETUP W E16 F16 F15 F13 D4 P4 Q4 R4 R5 S5 Q9 Q12 L16 
SETUP B D17 C16 D15 E15 D12 S4 S3 R3 Q3 O3 N3 R6 R16 P17 
MARK A@E18 C@P6 B@C6
COM
Problem 128. White to play.  

Where should White play: at A, B, or C ? 
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W 1 P6
MARK \t@N3
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

In response to the marked stone, White 1 is the proper response.
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  VAR
  W 1 E18
  MARK A@C6
  COM
  Failure.

  Locally, both White 1 and White A are big moves, but ...
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  B 2 S6
  COM
  ... if Black is allowed to play 2 ...
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  W 3 Q6
  B 4 Q7
  COM
  ... and 4, the right side could be thrown into confusion.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 C6
  COM
  Failure.

  Also wrong.
  <=
  ENDCOM
  ENDVAR
B 2 C6
COM
As expected, Black will play 2 ...
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W 3 F4
B 4 D9
COM
... and 4, but ...
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W 5 P15
COM
... White will cap at 5, and suddenly a white moyo emerges in
the center.
<=
ENDCOM