Answer:
Anaphase 1 of meiosis.
Step-by-step explanation:
Alleles are the alternative form of the same gene and present on the same chromosome. The alleles get separate at the time of meiosis.
The separation of homologous chromosomes during Anaphase 1 allows the separation of alleles of a particular trait. The new combination of allele is possible during thus phase.
Thus, the correct answer is Anaphase 1.