Which of the following statements about tolerance range is true?

a.

tolerance range is different for different organisms.

b.

the tolerance range is the total number of organisms that can be supported by an ecosystem.

c.

tolerance range is affected by biotic factors in an ecosystem.

d.

the available water supply does not impact an organism’s tolerance range.

The answer is a. Tolerance range is different for different organisms. 

Tolerance range is range of abiotic factors that must be maintained in order for species or populations to survive and function normally. Tolerance range is different for different organisms. It is affected by abiotic factors in an ecosystem. These abiotic factors could be available water supply, temperature, climate, etc.

Choice b could not be the right answer because  the total number of organisms that can be supported by an ecosystem is known as carrying capacity.