Why do flying bees buzz? 1. they move their wings at audible frequencies. 2. they have special wings that make sounds. 3. the buzz comes from their heads; they make a buzzing noise to communicate with each other?

The correct answer is 1. they move their wings at audible frequencies.
Bees and other flying insects move their wings at a very fact pace in order to be able to fly properly. Given that this movement is rather rapid, it causes a sound to be heard due to vibrations in the air. Humans perceive those sounds as buzzing, which is why it is said that bugs buzz as they are flying, when in fact it is just air vibration.