The saprotrophs are most essential in ________ food chain.

Step-by-step solution

Saprotrophs are organisms that obtain their nutrition from dead and decaying organic matter. They play a primary and essential role in the detritus food chain, which begins with dead organic material (detritus) rather than living plants. In this food chain, saprotrophs (such as fungi and bacteria) break down complex organic matter into simpler inorganic substances, recycling nutrients back into the ecosystem. Answer: detritus