Explanation: fitness can be thought of as fit for purpose. The most fit for purpose organism is the one best adapted to its environment.
Nevertheless, all the options are characteristic of adaptation
It is not particularly useful to discuss natural selection in terms of individuals and not populations. An advantageous mutation in one individual is the theoretical starting point for a better adapted population, but adaptation happens in a population very slowly if at all if it depends on a single individual. The smaller the population, the higher the probability that the adaptation will be eliminated by chance.
Yes, Jan should undergo genetic sequencing.BRCA1/BRCA2 are the causes of 20-25% of all hereditary breast cancers, so if Jan's mother and sister both have breast cancer, then the odds are that she has BRCA1 as well.
