Three Hfr strains that are e+ f+ g+ h+ i+k are mixed with F- strains (e-, f-, g-, h-, i-, k-). Interrupted mating was carried out and the sequence each Hfr strain consistently passed to F- strains are______.

a. Recorded for analysis
b. Used for mutation studies
c. Exchanged via conjugation
d. Sorted based on genotype