During synapses, chromatids in homologous pairs of chromosomes often twist around each other, break, exchange segments, and rejoin. This process usually contributes to:
A. the production of identical twins.
B. increased variability in offspring.
C. the formation of polyploid offspring.
D. nondisjunction of homologous chromosomes.
The concept described in the question is crossing-over. It is one way that increases variety in offspring. It occurs during meiosis when the replicated homologous chromosomes are in close contact with each other during synapses.