The detritus food chain (DFC) has _____ at the first trophic level.

The correct answer is Option (2) → Dead organic matter

Option (2) Dead organic matter — Correct. Of the options, only dead organic matter fits; the grazing food chain (GFC) is the one that starts from autotrophs.

NCERT Extract:
Energy Flow – “The detritus food chain (DFC) begins with dead organic matter. It is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria. They meet their energy and nutrient requirements by degrading dead organic matter or detritus. These are also known as saprotrophs (sapro: to decompose).”