Genes $A$ and $B$ are linked. What will be the genotype of the offspring produced by a cross between $AB/ab$ and $ab/ab$?

In $Drosophila$,long wing and broad abdomen characters are dominant over vestigial wing and narrow abdomen characters. $A$ pure-breeding $Drosophila$ with long wings and broad abdomen is crossed with a pure-breeding vestigial-winged and narrow-abdomened $Drosophila$. Two of the $F_1$ individuals were crossed,and the following results were produced in the $F_2$ generation: $482$ $Drosophila$ with long wings and broad abdomen,and $154$ $Drosophila$ with vestigial wings and narrow abdomen. Which one of the following is illustrated by these results?

Provide the experimental verification of the chromosomal theory of inheritance.

$A$: Morgan's cross $III$ was conducted in $Drosophila$ to locate genes on the chromosome for white eye color.
$R$: The cross was done between red-eyed hybrid female and white-eyed male.

In which of the following is the phenomenon of crossing over $NOT$ observed?

Which of the following represents the frequency of recombination between two genes that are inversely proportional to the strength of linkage?