Read the following passage carefully, and then select the best option A, B, C or D to complete it

Conservation, sustainable use and protection of (21) _______ resources including plants, animals, mineral deposits, soils, clean (22) _______, clean air, and fossil fuels such as coal, petroleum, and natural gas. Natural (23) _______ are grouped into two categories, renewable and nonrenewable. A (24) _______ resource is one that may be replaced over time by natural processes, (25) _______ fish populations or natural vegetation, or is inexhaustible, such as (26) _______ energy. The goal of renewable resource conservation is to ensure (27) _______ such resources are not consumed faster than they are (28) _______. Nonrenewable resources are those in limited supply that cannot be replaced (29) ______ can be replaced only over extremely long (30) _______ of time. Nonrenewable resources include fossil fuels and mineral deposits, such as (31) _______ ore and gold ore. Conservation activities for nonrenewable resources focus (32) _______ maintaining an adequate supply of these resources well into the future.

Natural resources are conserved for their biological, economic, and recreational values, (33) _______ their natural beauty and importance to local cultures. (34) _______, tropical rain forests are protected for their important role in both global ecology and the economic livelihood of the local culture; a coral reef may be (35) _______ for its recreational value for scuba divers; and a scenic river may be protected for its natural beauty....