Most people have heard the sound of bees among flowers. Bees live almost everywhere in the world except in the Arctic areas. Many kinds of agriculture depend on these small, social insects. Without bees, fruit and nut growers as well as many other farmers would not have a crop. There are more than 20,000 kinds of bees. But only honey bees make enough honey for people to use. Honeybees are highly-organized social insects. They work together in a group, called a colony . Each colony lives in a hive . It contains one queen bee -- she lays all the eggs from which the members of the colony come. Each colony has only a few hundred males, called drones. The majority of all bees in a colony are workers, which are all females. Bees even have a special stomach, called a honey stomach,  which is used to store sweet fluid that the bees gather from flowers. Bees also have long hairs on their body and legs. These hairs capture pollen  as bees go from flower to flower. Some of the pollen is taken back to the hive. Some, however, is passed to the next flower. This is how many plants are fertilized. Pollen is the reproductive material of plants. Many important agricultural crops depend on bees for fertilization. Inside their hives, bees store sweet liquid from flowers and pollen as well. They may even gather sweet liquid from some other kinds of insects. These kinds of sweet liquid are also stored in the hive. Bees make honey through a process. They add liquid from their own mouths to sweet liquid into simple sugar. As the honey is stored, it dries. It becomes thicker and darker. Although bees are often thought of as honey makers, they provide a surprising number of products. Also, their greatest economic value is in fertilizing crops-not in making honey. The word "fertilize" in the sentence "This is how many plants are fertilized" probably means "  _  ".
to make plants strong and productive to make soil rich for plants to start the development of young flowers to introduce pollen into plants