Polygenic traits are controlled by:

The correct answer is Option (3) → Three or more genes  

Polygenic inheritance involves the influence of multiple genes on a single phenotypic trait. Polygenic inheritance is an inheritance pattern controlled by three or more genes (multiple genes) and the graded phenotypes are due to the additive or cumulative effect of all the different genes of the trait. An example of human skin colour to understand the phenomenon of polygenic inheritance.