Concept:Wind speed is measured by a specific meteorological instrument called an anemometer.Explanation:A wind vane only indicates the direction from which the wind is blowing.An anemometer is designed to measure the speed or velocity of the wind.A photometer is used to measure the intensity of light.A barometer measures atmospheric pressure, not wind speed.Hence, among the given options, the anemometer is the instrument used for measuring wind speed.Answer:B. anemometer