Unlike secondary succession, primary succession
a. occurs in an area where existing communities still exist.
b. leads to an increased number of different species over time.
c. has the challenge of occurring in areas where no community exists at all.
d. proceeds at a much faster rate.

The correct answer would be C. has the challenge of occurring in areas where no community exists at all.

Primary succession is a type of ecological succession which in an environment which lacks soil, vegetation, or other organisms.  

In other words, it occurs in the area where no community exists at all due to which it takes a longer period of time to develop an ecosystem.

Pioneer species include algae, lichens, and fungi which are gradually replaced by small plants such as grasses and shrubs.  

Nutrients and water level increase gradually with the progression of succession and grasses, herbs, ferns, and trees accumulate the area.  

It attracts different animals which leads to the development of a complex community.

a chair, a bed, and a toothbrush

explanation:

i was told this before by a teacher, so yeah