In 1956, Indonesia-born American cytogeneticist Joe Hin Tjio announced that the exact number of human chromosomes is _____.

Correct option is A

The correct answer is (a) 46.
· In 1956, Joe Hin Tjio, working with Albert Levan, discovered that the correct number of human chromosomes is 46.
· This discovery corrected the previously held belief that humans had 48 chromosomes.
· Tjio and Levan used improved techniques in chromosome preparation and staining, which allowed them to accurately count the chromosomes in human cells.
· The finding was a significant milestone in the field of cytogenetics and has profound implications for the understanding of human genetics, including genetic disorders and inheritance patterns.
· This discovery is foundational for genetic research and diagnostics.