When John Cairns First Visualized the Replication of E

Multiple Choice

When John Cairns first visualized the replication of E.coli chromosomes in 1963 what did he conclude? 1.The chromosomes of E.coli are circular structures that exist as u-shaped intermediates during replication.
2) The unwinding of the two complementary parental strands and their semiconservative replication occur simultaneously or are closely coupled.
3) Semiconservative replication of the E.coli chromosome started at a specific site,and proceeded sequentially and unidirectionally around the circular structure

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these