Which of the following is a common item used to smoke bees before hive manipulation?

A bee smoker is an essential tool in beekeeping used to calm bees before hive manipulation. When smoke is introduced into the hive, it triggers a natural response in bees that leads them to become less aggressive. The smoke masks pheromones associated with alarm, reducing their defensive behaviors. As a result, beekeepers can work with the hive with a lower risk of stings and without causing undue stress to the colony.

Other potential items like wood chips or leaves can indeed create smoke, but they are not specifically designed for this purpose. A bee smoker is a specialized device that allows beekeepers to create a controlled and steady supply of smoke, maximizing the calming effect on the bees. Using paper can also produce smoke, but similar to wood chips or leaves, it's less effective and more difficult to manage compared to a purpose-built bee smoker. Thus, the bee smoker is recognized as the most efficient and standard method for producing smoke in the context of beekeeping.