A number of lower trophic levels organisms are feed by higher trophic levels constitute the____

Organisms of a higher trophic level feeding on several types of organisms belonging to a lower trophic level constitute a food web. It is a complex network of many interdependent food chains. The food chain is a single chain of organisms feeding on one another. The food pyramid is a diagrammatic representation of the type and proportion of food items eaten by human beings for a healthy life. An ecosystem is a combination of living and non-living components.

Hence option (a) food web is correct.