Arrange the contributions of the following scientists chronologically…

The correct answer is Option (2) → (C), (B), (D), (A)

(C) Gregor Mendel — comes first. He did his hybridisation experiments on garden peas for seven years (1856-1863) and proposed the laws of inheritance. His work was not accepted by the scientists of his time.

(B) von Tschermak — comes second. In 1900 he, de Vries and Correns independently rediscovered Mendel’s results.

(D) Theodore Boveri — comes third. By 1902 the movement of chromosomes in meiosis had been worked out. Boveri and Sutton saw that chromosomes behave in the same way as genes, and this gave the chromosomal theory of inheritance.

(A) Thomas Hunt Morgan — comes last. He and his colleagues tested the chromosomal theory by experiments on the fruit fly Drosophila melanogaster. This led to the discovery of linkage and recombination.

NCERT Extract:
Chromosomal Theory of Inheritance – “… In 1900, three Scientists (de Vries, Correns and von Tschermak) independently rediscovered Mendel’s results on the inheritance of characters. Also, by this time due to advancements in microscopy that were taking place, scientists were able to carefully observe cell division. This led to the discovery of structures in the nucleus that appeared to double and divide just before each cell division. These were called chromosomes (colored bodies, as they were visualised by staining). By 1902, the chromosome movement during meiosis had been worked out. Walter Sutton and Theodore Boveri noted that the behaviour of chromosomes was parallel to the behaviour of genes and used chromosome movement (Figure 4.8) to explain Mendel’s laws (Table 4.3).”
Chromosomal Theory of Inheritance – “… Following this synthesis of ideas, experimental verification of the chromosomal theory of inheritance by Thomas Hunt Morgan and his colleagues, led to discovering the basis for the variation that sexual reproduction produced.”