Investment by the government of iran in irrigation systems is investment in
a. natural resources.
b. capital goods.
c. human resources.
d. human capital.

Investment by the government of Iran in irrigation systems is investment in a)natural resources. Natural resources are defined as "all that exists without the actions of humankind." Although irrigation is the un-natural so to speak, since it is the artificial application of water to the land or soil, the soil is a natural resource and is deemed in good enough condition to be able to go through the irrigation process.