Which of the following statements are incorrect regarding food chain?…

The correct answer is Option (2) → (A) and (D) only

(A) Primary carnivores are the tertiary consumers — False. Primary carnivores eat herbivores, so they are secondary consumers.

(B) The flow of energy form the sun to producers and then to consumers is unidirectional — True. Energy passes one way and is not recycled.

(C) The death of the organism is the initation of detritus food chain — True. The detritus food chain begins with dead organic matter.

(D) Plant are the primary consumers as they utilise the solar energy for making food — False. Plants make their own food, so they are producers; the herbivores that eat them are the primary consumers.

NCERT Extract:
Ecosystem – Structure and Function – “… The consumers that feed on these herbivores are carnivores, or more correctly primary carnivores (though secondary consumers). Those animals that depend on the primary carnivores for food are labelled secondary carnivores.”
Energy Flow – “… All organisms are dependent for their food on producers, either directly or indirectly. So you find unidirectional flow of energy from the sun to producers and then to consumers.”
Energy Flow – “The detritus food chain (DFC) begins with dead organic matter.”