Mendel did not recognize the linkage phenomenon in his experiments because

Crossing over is advantageous because it brings about

In a fruit fly,the $X$-chromosome linkage map has a total length of $66$ units,with the yellow body gene $(y)$ at one end and the bobbed hair gene $(b)$ at the other end. What will be the recombination frequency between these two genes $(y$ and $b)$?

In a chromosome map of maize,two genes $R$ and $Y$ are located very close to each other. When $RRYY$ and $rryy$ genotypes are crossed,the $F_2$ generation analysis shows:

How many linkage groups are present in Drosophila?

Based on which of the following did Morgan observe characteristics similar to Mendel's analysis experiments in the fruit fly Drosophila?