Which scientists proposed the coupling and repulsion theory?

Give scientific reasons: Linkage and crossing over of genes are alternatives of each other.

Select the incorrect statement$(s)$ from the options given below with respect to dihybrid cross.
$I.$ Tightly linked genes on the same chromosome show higher recombinations.
$II.$ Genes far apart on the same chromosome show very few recombinations.
$III.$ Genes loosely linked on the same chromosome show similar recombinations.

Which method can be used to determine the location of specific genes on a chromosome?

Who mapped the position of genes on chromosomes by using the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes?

There are three genes $a, b,$ and $c$. The recombination frequency between $a$ and $b$ is $20\%$,between $b$ and $c$ is $28\%$,and between $a$ and $c$ is $8\%$. What is the possible arrangement of these genes on the chromosome?