Natural resources are raw materials that have not been processed,and the original appearance are kept when it is collected.
Let's look into the choices one by one:
A) carpenter - Carpenter is a kind of occupation that use natural resources, wood, to produce different wood products. This is not a natural resource.
B) chairs - Though made out of natural resource, this is not natural resource itself as it is processed, undergoing the procedure of being cut down,trimmed,put together etc.
C) mechanic - This is is an occupation who operate machine this not a natural resource.
D) trees - Trees are the original form of the organism and can be processed and used, this is a common natural resource.
Therefore the answer is D) trees.
Hope it helps!