As Additional Evidence That U238 Has an Unusual Mode of DNA

Multiple Choice

As additional evidence that U238 has an unusual mode of DNA replication, you conduct still another Meselson-Stahl type experiment, again allowing the virus to replicate in the presence of "heavy" nitrogen until both strands of its genome are "heavy." This time you allow U238 to undergo three complete rounds of replication in the presence of "light" nitrogen. What ratio of "heavy" to "light" viral DNA would you expect to find after three complete rounds of replication?

A) 1:7
B) 2:6
C) 4:4
D) 6:2
E) 7:1