A small source of sound moves on a circle as shown in figure and an observer is sitting at O. Let `v_1,v_2,v_3` be the frequencies heard when the source is at A,B and C respectively.

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A. `upsilon_(1) gt upsilon_(2) gt upsilon_(3)`
B. `upsilon_(1) = upsilon_(2) gt upsilon_(3)`
C. `upsilon_(2) gt upsilon_(3) gt upsilon_(1)`
D. `upsilon_(1) gt upsilon_(3) gt upsilon_(2)`