Which of the following statements is correct about saprotrophs ?

The correct answer is Option (4) → They depend on dead organic material for their food needs.

Saprotrophs — the fungi and bacteria that act as decomposers — secrete enzymes onto dead plant and animal remains and absorb the digested products. Feeding on detritus in this way, they release the locked-up nutrients back into the soil and water and close the biogeochemical cycles.

They therefore do not feed on living plants or zooplankton, and they are not primary consumers; primary consumers are the herbivores that graze on living producers.