How many phenotypes can be expected from a polygenic inheritance pattern for a character involving three gene pairs?

The correct option is D 7
If the occurrence of a trait is controlled by several genes, then the inheritance pattern it follows is polygenic inheritance.
Unlike Mendelian trait inheritance, it is a quantitative trait that is formed by cumulative effects of the intermediate genes as well.
There is a numerical formula that is used to calculate the number of phenotypes in polygenic inheritance = 2n+1
Where n = number of gene pairs involved
In the given question, $n=3$
$\Rightarrow (2\times 3)+1$
$\Rightarrow 7$
Therefore, 7 different types of phenotypes can be expected in the progeny.