Regarding detritus food chain.

I. The detritus food chain starts with dead organic matter, with decomposers known as saprophytes occupying the first trophic level.

II. The energy in the detritus food chain originates from the sun.

III. In terrestrial ecosystems, a much larger portion of energy is transferred through this type of food chain.

Which of the statements given above are correct?

 I and III

The correct answer is Option  (2) - I and III

• Statement I is correct: The detritus food chain begins with dead organic matter (detritus) and decomposers, such as bacteria and fungi, which are called saprophytes. They occupy the first trophic level.
• Statement II is incorrect: The energy for the detritus food chain does not come directly from the sun but rather from the organic matter formed by primary producers (plants) that previously harnessed solar energy through photosynthesis.
• Statement III is correct: In terrestrial ecosystems, a large fraction of energy flows through the detritus food chain as it deals with the recycling of nutrients from dead organisms.

Thus, I and III are correct, and II is incorrect.