The strength of winds is measured with the help of

ANS:A - Benfort scale

A) The Beaufort scale measure that relates wind speed to observed conditions at sea or on land.
It's full name is the Beaufort wind force scale.

B) Wind indicator is a small weather vane or arrow that gives an indication of the current apparent wind direction.

C) A barometer is a scientific instrument used to measure atmospheric pressure, also called barometric pressure.