A small source of sound moves on a circle as shown in figure and an observer is sitting at O. Let ${\mathrm{\nu }}_1,{\mathrm{\nu }}_2,{\mathrm{\nu }}_3$ be the frequencies heard when the source is at A, B and C respectively

• A

  ${\mathrm{\nu }}_1> {\mathrm{\nu }}_2> {\mathrm{\nu }}_3$

• B

  ${\mathrm{\nu }}_1= {\mathrm{\nu }}_2= {\mathrm{\nu }}_3$

• C

  ${\mathrm{\nu }}_2> {\mathrm{\nu }}_3> {\mathrm{\nu }}_1$

• D

  ${\mathrm{\nu }}_1> {\mathrm{\nu }}_3> {\mathrm{\nu }}_2$