Cultured Mammalian Cells Grown in Thymidine for Many Generations Were

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU) , which replaces thymidine in DNA. After one round of replication, what does the DNA look like?

A) All chromatids have one strand that contains BrdU and one strand that contains thymidine.
B) All chromatids have two strands that contain BrdU.
C) Half of the chromatids have two strands that contain BrdU and half have two strands lacking BrdU.
D) Both of the strands of each chromatid contain mixtures of BrdU and thymidine.
E) All chromatids lack BrdU.