The principle that best aligns with Mendel's law of segregation is:
C: alleles belonging to the same gene will never end up in the same gamete during meiosis.
Mendel's law of segregation states that during the formation of gametes (meiosis), the two alleles for a gene segregate (separate) from each other so that each gamete carries only one allele for each gene. This option correctly reflects that principle.
Options A and D refer to crossover and independent assortment, respectively, while option B incorrectly mentions mitosis instead of meiosis and is also misleading in the context of segregation.