Assertion : When yelow bodied, white eyed Drosophila females were hybridised with brown-bodied, red eyeed males , and `F_(1)` progeny was intercrossed, `F_(2)` ratio deviated from `9:3:3:1`
Reason : When two genes in a dihybrid are on same chromosome, the proportion of parental gene combinations are much higher than the non-parental type

Answer

A

Explanation

In Drosophila, the genes for body and eye colour are located on X chromosome. When two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combination are higher than non-parental type. This occurs due to physical association or linkage of the two genes while non-parental gene combinations due to recombination between genes. Thus, linkage and recombination deviates the ratio form Mendelian ratio of a dihybrid cross `(9:3:3:1)`