Why might you want to use a single fixed pulley?
a to reduce the force needed to raise objects
b to raise or lower heavy objects
c
to raise or lower lightweight objects

d
to reduce the weight of lifted objects

answer:

explanation:

it is

Correct D) Competitive exclusion

Carrying capacity of an ecosystem may be defined as the total number of organism it can support. Biotic and abiotic factors such as available space, water, food and shelter  act as a limiting factor, which determine how many organism can live within a ecosystem.

The competitive exclusion principle states that two species that compete for same resources cannot stably coexist.

One among the two competitor will always have slight advantage over the other, it leads to extinction of other competitor or lead to an evolutionary shift of the inferior one to a different ecological niche. Therefore, competitive exclusion have least effect on the carrying capacity of an ecosystem.