Which even acconts for the probability that a particular allele will be packaged in agiven gamete

"The process of random chromosomes segregation" accounts for the probability that a particular allele will be packaged in a given gamete.

Explanation:

Genes arrive in little different forms for each trait and understood as alleles, basically generated by mutations. Meiosis shamble the alleles during gamete formation and fertilization results into the offspring with unique alleles combinations.

The alleles of a gene get isolated from each other when sex cells are produced during meiosis. Chromosomes are randomly segregated into four gametes during meiosis, so there is a quarter chance that a particular allele will be in a given gamete.