How does random fertilization add to the genetic variation?

The answer is exchange of genetic material between homologous chromosomes. Homologous chromosomes are comprised of chromosome sets of around a similar length, centromere position, and recoloring design, for qualities with the same comparing loci.

In genetics, random fertilization is a situation where fertilization occurs randomly with many possible outcomes. The fact that random fertilization has a large number of possible outcomes means that the resulting product can have a wide range of characteristics. This gives a rise to a great variation in the genetics of the product.

Essential for a scientist to do for credibility

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.

Distillation.  distillation is the correct answer.