Genic balance theory of sex was proposed by

The correct option is B Bridges
This theory was proposed by Calvin Bridges (1921). From his study on Drosophila he suggested that the X chromosomes carry factor for femaleness whereas autosomes “A” carry genes for maleness. Y chromosome does not take part in sex determination. From the picture it is clear that the genic balance is governed by the ratio of the number of X-chromosomes to the number of sets of autosomes in the zygote at fertilization. II the ratio is 1.0 the offspring develops into female, but if it is 0.5, then the offspring develops into male. If the ratio is intermediate between 1.0 and 0.5, the resulting individual is neither a male or nor a female but an inter sex. Super females have a ratio of 1.5 and super males have a ratio 0.33.

So, the correct answer is 'Bridges'.