Under what frequency ultrasonic machining is done?

1.	Under what frequency ultrasonic machining is done?
A.	5‚Äö√Ñ√∂‚àö√ë‚àö√Ü10 Hz
B.	5‚Äö√Ñ√∂‚àö√ë‚àö√Ü10 kHz
C.	12‚Äö√Ñ√∂‚àö√ë‚àö√Ü19 Hz
D.	19‚Äö√Ñ√∂‚àö√ë‚àö√Ü25 kHz
Answer» E.

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