The correct option is C (A)- (V), (B)- (IV), (C)- (I), (D)- (II)
Morgan studied heredity of different characters in Drosophila and identified linkage in genes of sex-linked characters. The linkage is the tendency of closely placed genes on a chromosome to stay together during inheritance (A-V).
Muller identified radioactive nature of X-rays and induced point mutations in the fruit fly Drosophila by exposing them to relatively high doses of radiation. It was concluded that radioactive particles traverse through the chromosomes and randomly affect the molecular structure of individual genes, making them either non-functional or with altered function (C-I).
Garner and Allard in 1920 observed that a variety of tobacco, Maryland mammoth exhibited flowering when the relative length of the day was shorter than the length of the dark period. They defined the length of the daily period of light to which a plant is exposed as ‘photoperiod’ and the process of induction of flowering in response to photoperiods as ‘photoperiodism’ (D-II).
Lysenko coined the term “vernalization” as the process of acquisition of ability of plants to flower by chilling treatment (B-IV).
Therefore, the correct answer is option C.