The correct option is B Primary metabolite
Primary metabolites are the essential metabolic intermediates of various metabolic reactions occuring in the plants which play a direct role in the growth and development of the plant.
Secondary metabolites are metabolic intermediates which do not play a direct role in the growth and development of plants. They perform additional functions such as defense and attracting pollinators.
Tertiary metabolites are rarely found. If they are found, they are usually compounds which are a result of interactions of primary or secondary metabolites among themselves or with each other.
Saponins are phytochemicals mostly found in vegetables.