Final answer:
Option B represents an example of positive interference: A single crossover stimulates further recombination. This enhances genetic variation by increasing the likelihood of additional crossovers during meiosis.
Step-by-step explanation:
The student's question relates to concepts of genetic recombination and crossover events during meiosis. Among the given options, the one that represents an example of positive interference is B) A single crossover stimulates further recombination. This is because positive interference implies that the occurrence of one crossover can increase the likelihood of additional crossovers, enhancing genetic variation. Crossing-over usually occurs during prophase I of meiosis, where non-sister chromatids of homologous chromosomes exchange segments of genetic material, resulting in recombinant chromosomes containing unique combinations of parental genes.
As illustrated in the figures and excerpts provided, recombination frequency is affected by the distance between genes on a chromosome; genes that are farther apart have a higher likelihood of undergoing crossover. The student's question addresses the phenomenon wherein certain mechanisms, such as crossovers, create diversity in genetic material passed to offspring.
Summarily, a recombination event that stimulates further recombination, as stated in option B, enhances the genetic diversity among gametes, which is fundamental to the process of genetic recombination in sexual reproduction.