Which one of the following is the correct sequence of a food chain?

Option (A) is correct because it accurately represents the unidirectional flow of energy in a marine food chain, starting with Diatoms (producers/phytoplankton), followed by Crustaceans (primary consumers/zooplankton), and ending with Herrings (secondary consumers/fish). Option (B) is incorrect because it places consumers before producers, which violates the fundamental ecological rule that energy must originate from autotrophs. This question tests the core concept of trophic levels and the hierarchical structure of a grazing food chain in an aquatic ecosystem.