Alleles which show independent effect are called

If two persons with $AB$ blood group marry and have a sufficiently large number of children,these children could be classified as $A$ blood group : $AB$ blood group : $B$ blood group in $1 : 2 : 1$ ratio. Modern techniques of protein electrophoresis reveal the presence of both $A$ and $B$ type proteins in $AB$ blood group individuals. This is an example of:

In cattle,when a cross results in offspring with roan (spotted) coat color,which of the following phenomena is demonstrated?

In shorthorn cattle,genes for red $(R_1)$ and white $(R_2)$ coat colour occur. Crosses between red $(R_1R_1)$ and white $(R_2R_2)$ produced $(R_1R_2)$ roan. This is an example of

. . . . . . is an intragenic interaction.

$A$ roan bull is crossed with three cows. Cow $A$ has the same genotype as the roan bull,cow $B$ is red,and cow $C$ is white. What should be the proportion of roan offspring in each group of cows?