Practice: Which of the following processes occurs when homologous chromosomes cross over in meiosis I?
a) Two sister chromatids get tangled, resulting in one re-sequencing its DNA.
b) Two sister chromatids exchange identical pieces of DNA.
c) Maternal alleles are "corrected" to be like paternal alleles and vice versa.
d) Corresponding segments of non-sister chromatids from homologous chromosomes are exchanged.