Cultured Mammalian Cells Grown in Thymidine for Many Generations Were

Multiple Choice

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 two rounds of replication,what would the DNA look like if replication were conservative?

A) All chromatids have one strand that contains BrdU and one strand that does not.
B) All chromatids have two strands that contain BrdU.
C) Half of the chromatids have two strands that contain BrdU and half of the chromatids have 2 strands lacking BrdU.
D) Both strands of each chromatid contain mixtures of BrdU and thymidine.
E) 75% of the chromatids have two strands that contain BrdU and 25% of the chromatids have 1 strand lacking BrdU and 1 strand containing BrdU.