Which best revises this sentence for clarity without changing its overall meaning?
During recent research, genetic researchers have isolated the gene that determines the natural times a
person sleeps and wakes.
A.
Genetic researchers recently isolated the gene that determines a person's natural sleep cycle.
B.
During research, genetic researchers have isolated the gene that determines the natural times a person sleeps and wakes.
C.
During recent research, genetic researchers have isolated the gene that determines times a person sleeps and wakes.
D.
During recent research, genetic scientists who research have isolated the gene that determines the natural times a person sleeps and wakes.