Considerable evidence indicates that the null model of community structure is incorrect because .
a. each species responds independently of other species to the prevailing physical environment.
b. interactions among species have no significant influence on community structure.
c. when one species is removed, the populations of the other species are unaffected.
d. species interactions modify the fundamental niche of the species involved, influencing their relative abundance and, in some cases, their distribution.

Explanation:

Null model of community structure describes the communities which occur in the absence of a mechanism

Fundamental niche represents all the environmental conditions where a species is able to live or can live, there are no ecological barriers present in this type of niche

Species interactions modify the fundamental niche as a result distribution and abundance of species changes, ecological barriers comes into existence and fundamental niche changes into realized niche where species actually lives

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b. the carbon cycle ensures living things have a source of hydrogen