Crossing over is

The term “linkage” was coined by

Morgan hybridised yellow-bodied, white-eyed females to brown-bodied, red-eyed males and intercrossed their $F_{1}$ progeny. He observed that

$(a)$ $F_{2}$ ratio was deviated very significantly from the $9 : 3 : 3 : 1$ ratio

$(b)$ Both genes did not segregate independently of each other

$(c)$ Recombinant types are not obtained in $F_{2}$ generation

$(d)$ Both genes segregate independently of each other

Select the correct set of statements :

Exchange of genetic material between chromatids of homologous chromosomes during meiosis is called

Linkage decreases the frequency of

Percentage of recombination between $A$ and $B$ is $9\%$ and $C$ is $17\%$, $B$ and $C$ is $26\%$, then the arrangement of genes is