In 1956 Tijo and Levan First Successfully Counted Human Chromosomes

Multiple Choice

In 1956 Tijo and Levan first successfully counted human chromosomes. The reason it would have taken so many years to have done so would have included all but which of the following?

A) Watson and Crick's structure of DNA was not done until 1953.
B) Chromosomes were piled up on top of one another in the nucleus.
C) Chromosomes were not distinguishable during interphase.
D) A method had not yet been devised to halt mitosis at metaphase.