A scientist investigated DNA replication in two groups of cells, labeled A and B. She injected radioactively labeled nucleotides into cells of each group and allowed DNA replication to begin. When replication was halfway completed, she injected a drug into the cells to stop replication. She then examined the cells to determine the distribution of the newly-synthesized DNA. She found each cell of group A had many segments of new DNA in its nucleus, while each cell of group B had a single segment of new DNA in its cytoplasm.

What can the researcher conclude about the cells?
A.
The cells in group B are prokaryotic because they replicate their DNA in the cytoplasm.
B.
The cells in group A are eukaryotic because they replicate their DNA in the cytoplasm or nucleus.
C.
Group A cells are prokaryotic because they must have many origins of replication.
D.
Group B cells are eukaryotic because they must have a single origin of replication.