The accessory chromosome explanation was proposed by

Answer: Option B

The accessory chromosome explanation was proposed by Mc clung.
Clarence Erwin McClung was an eminent American zoologist and prairie pioneer cytologist who discovered the role of chromosomes in sex-determination.
In 1901 McClung hypothesized that sex determination in grasshoppers is dependent upon the number of X chromosomes within a cell. Maleness in grasshoppers is determined by the absence of a second X chromosome (XO), while femaleness is induced by the presence of two X chromosomes (XX). This theory helped to prove that chromosomes carry genetic information that determines phenotype.