Natural Selection

The selection pressure here is predation by foxes. In a snowy environment, visibility of prey is the key survival factor.

White fur provides camouflage against snow, making white rabbits harder for foxes to spot. Brown rabbits are more visible against white snow and are therefore more likely to be eaten before they can reproduce.

White rabbits survive longer and reproduce more, passing on their alleles for white fur to offspring. Brown rabbits are removed from the population by predation before reproducing as often.

Over many generations, white fur becomes more common in the population — this is natural selection favouring the camouflaged variant.

The question asks which fur colour will become more common in a snowy environment where foxes are predators — this is a classic natural selection scenario.

Brown rabbits are stronger and faster is incorrect reasoning. 'Fitness' in biology means reproductive success, not physical strength. In snow, brown rabbits are more visible to predators, so this option is wrong.

Rabbits can choose their own colour is biologically impossible. Fur colour is a genetic trait; rabbits cannot choose it. Equal proportions would only persist if neither colour had an advantage, which is not the case here.

All rabbits develop spotted fur implies a goal-directed process — a common misconception. Natural selection acts on existing variation, it does not create new traits on demand.

The correct answer is that white fur becomes more common because white rabbits are camouflaged, survive longer, and pass on white fur alleles more often.

The question asks which observation explains why not all offspring can survive. This links overproduction with competition for limited resources.

Darwin observed that organisms produce far more offspring than the environment can support. Because resources like food, water, and space are limited, individuals must compete, and many die before reproducing.

The observation that describes the consequence of overproduction — the competition and resulting deaths — is specifically called the struggle for survival (or competition). Overproduction sets up the conditions, but the struggle is what directly causes differential survival.

The correct answer is struggle for survival, because it describes how competition for limited resources means many individuals die before reproducing.

The question is asking which Darwin observation explains why not all offspring survive — linking resource limits to death.

Variation explains why some individuals do better than others, not why resources are limited and not all can survive. Variation is the raw material, not the cause of death.

The option stating overproduction directly causes all offspring to die immediately is incorrect. Overproduction creates the conditions for competition, but does not directly kill offspring instantly — many simply fail to survive due to competition.

Differential reproduction describes the outcome — that some individuals reproduce more than others. It does not explain the mechanism (limited resources) causing deaths.

The correct answer is struggle for survival — more offspring are produced than resources can support, so competition leads to many deaths before reproduction.