The diagram below shows homologous chromosomes during prophase I of meiosis. Which of the following correctly describes the process being illustrated?
a
Segregation of sister chromotids
b
Condensation and segregation of alleles, Segregation of sister chromotids
c
Mutation in which the DNA content of the gene is altered
d
Crossing over in which alleles are exchanged
d
Crossing over in which alleles are exchanged