Using the passage as a guide, it can be understood that which of the following
trees are most closely related to one
another?
A. pines and oaks
B. oaks and elms
C. maples and firs
D. pines and maples

If you take a walk through the woods, you will probably notice many varieties of trees. Have you ever thought about how these trees are different? Scientists do. Scientists use the differences and similarities they find to classify the many types of trees. Sorting trees into categories helps us to understand how different trees are related to one another.

Perhaps the most significant difference between trees is that some lose their leaves in the fall, while others do not. Trees that lose their leaves are called deciduous trees. Trees that do not lose their leaves are called coniferous trees. Some deciduous trees you might recognize are oaks, maples, and elms. Some coniferous trees you may know are pines, spruces, and firs.

Another important difference among trees is how they protect their seeds. If a tree has flowers, this is likely because it is using them to protect their seeds. These trees are called angiosperms. Some angiosperms you might recognize are maples and oaks. On the other hand, some trees put their seeds inside cones to protect them. These trees are called gymnosperms. If you have been to the eastern part of the United States, then you have probably seen a pine tree. Pine trees keep their seeds in cones, so they are gymnosperms too.

Scientists also categorize trees based on other characteristics like their bark, the types of fruit they produce, and their size and shape.