The number of linkage groups in a cell having $10$ pairs of chromosomes is.....

There are three genes $a, b, c$ with percentage of crossing over between $a$ and $b$ is $20\%$,$b$ and $c$ is $28\%$,and $a$ and $c$ is $8\%$. What is the sequence of genes on the chromosome?

The scientists who proposed the theory of linkage are

Who put forward the "Theory of linkage"?

What happens in the process of variation?

Select the correct statement regarding dihybrid crosses and linkage.