This is because the melanocytes are located in the stratum basale. Lighter-skinned people usually have low basal levels, and exposure to UV radiation causes an increase which makes skin darker.
You question is incomplete, because I cannot read the final option - it isn't finished.
However, based on the options I can read, the best <span>sentence for an article about whether or not certain genes play a favorable role in human evolution is the third one - j</span><span>umping genes have the unsavory reputation of causing genetic mutation or cancerous cell growth.
The other two options say nothing about the role of certain genes, they just state some facts. </span>
Sun grows plants which feed animals or feeds the animals prey
<span>The stage at which all the cells show crossover chromosomes is meiotic prophase I. The crossover is the exchange of genetic material between homologous chromosomes. Homologous chromosomes are present in the meiosis I. Regarding the phase of meiosis I, it is expected that the crossover takes place in meiotic prophase I since homologous chromosomes pair up in the prophase.</span>