In 1956 Tijo and Levan First Successfully Counted Human Chromosomes

Multiple Choice

In 1956 Tijo and Levan first successfully counted human chromosomes. What is the reason it took so many years to do so?

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.
E) Chromosomes were piled up on top of one another in the nucleus, chromosomes were not distinguishable during interphase, and a method had not yet been devised to halt mitosis at metaphase.