Which of the following characteristics cannot be observed in the progeny if linkage is present?

The distance between two genes in a chromosome is measured in cross-over units,which represent:

Complete linkage is observed in.....

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?

Generation of non-parental gene combinations is termed as

$A$ : In block inheritance of all genes located on the same chromosome may occur in some organisms.
$R$ : Dihybrid test cross will have only two phenotypes.