$F_2$ generation of a cross between two white flowered strains of Sweet Pea yields 9 purple flowered plants : 7 white flowered plants. This is an example of

The correct option is A Complementary genes

A white flower Sweet Potato(CCpp) is crossed with another white flowered Sweet Potato(ccPP). In the F1 generation, Purple flowered Sweet potato plants are formed. When these plants are subjected to self pollination, in the F₂ generation, 9 plants with purple flowers and 7 plants with white flowers are formed. It is complementary genes.

So, the correct option is ‘Complementary genes’.