This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Crossing over, true is; 
Select and explain. 
A. Occurs during diplotene stage, B. Between non sister chromatids of homologous chromosomes, C. Between sister chromatids of homologous chromosomes, D. Between non homologous chromosomes sister chromatids
B: Between non sister chromatids of homologous chromosomes
Answer: B: Between non sister chromatids of homologous chromosomes 
Explanation: Crossing over is the exchange of genetic material between non sister chromatids of homologous chromosomes occuring during pachytene stage of prophase I of meiosis.Recombination of genes in the same chromosome is brought about by crossing over. Ref: PRINCIPLES OF GENETICS, By Eldon John Gardner, Michael J. Simmons, D. Peter Snustad, 8th Edition, Page 163