Which one of the following is NOT a condition necessary for natural se

Which one of the following is NOT a condition necessary for natural selection to occur?

More organisms are born than can survive
Organisms should not vary in their characteristics within a species
Variation is inherited
Differences in reproduction and survival are due to variation among organisms
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UPSC Geoscientist – 2021
For natural selection to occur, organisms *must* vary in their characteristics within a species. Variation is the raw material upon which selection acts.
The necessary conditions for natural selection are: variation among individuals, inheritance of variation, differential survival and reproduction based on that variation, and often, limited resources leading to competition (more offspring born than can survive).
If there were no variation within a species, all individuals would be identical, and there would be no basis for differential survival or reproduction based on traits, thus no natural selection leading to evolutionary change.