Double cross over involving ________ strands result in 100% recombinant

double-cross-over-involving-strands-result-in-100-recombinant

Double cross over involving ________ strands result in 100% recombinant strands.

A. 1

B. 2

C. 3

D. 4

This question was posed to me during a job interview.

My question is based upon Linkage and Crossing Over in section Genetic Recombination of Cytogenetics

Right option is D. 4

The best I can explain: Double cross over event between for strands will result in all the strands exchanging their genes. Thus, all the resultant will be recombinant so recombination frequency is 100%.