The correct option is B Both assertion and reason are true but reason is not the correct explanation of assertion.
Secondary metabolites are compounds such as alkaloids, rubber, essential oils, antibiotics, pigments, scents, gums, spices etc. present in plant, fungal and microbial cells. Secondary metabolites are biosynthetically derived from primary metabolites and are accumulated in smaller quantities than primary metabolites. In plants, they are synthesized in specialized cell types and at distinct developmental stages, making their extraction and purification difficult and expensive. Secondary metabolites can be produced on a large scale using tissue culture techniques.