INSIGHT UPSC QUIZ

ANS. (C) 
A food chain is a linear sequence of links in a food web starting from a trophic species that eats no other species in the web and ends at a trophic species that is eaten by no other species in the web. A food chain differs from a food web, because the complex polyphagous network of feeding relations is aggregated into trophic species and the chain only follows linear monophagous pathways. A common metric used to quantify food web trophic structure is food chain length. In its simplest form, the length of a chain is the number of links between a trophic consumer and the base of the web and the mean chain length of an entire web is the arithmetic average of the lengths of all chains in a food web. Food chains were first introduced by the African-Arab scientist and philosopher Al-Jahir in the 9th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept.