Question

The smallest unit that can evolve through natural selection is
A. Cell
В. Clade
C. Organism
D. Population
E. Species

Answer 1

Hint:Evolving through natural selection means the appearance of changed traits or as we call it, an evolution that selectively gives an advantage to the organisms of a particular species evolved.

Complete solution:
The differently evolved organism is able to adapt better and are better suited to the environment than the ones without the evolutionary trait and are thus more successful to breed, propagating their evolutionary characters while the one without is less suited eventually diminishes.
For evolution to be defined we need a group of organisms belonging to the same species. A population is an apt measure as it consists of a group of organisms belonging to the same species in a common geographical area, allowing inbreeding and allele exchanges. At this level only can the evolution of a section can be seen as they fare better than their counterparts by natural selection.

So, the correct answer to the question is option D.

Additional information:
Natural selection is a mechanism of evolution that was proposed by Darwin. It explains that populations evolve so that they are better suited to their surroundings over time.
All characters evolved may be suited to one particular environment but may not suit other environments.

Note: In the entire population, we will see evolution by natural selection as a section with the new better adapting traits will remain fit and survive better, producing more offspring, while the other section will fail to proliferate as much and fade.