Answer:
The correct answer is option A, Organic matter
Step-by-step explanation:
Autotrophs are basically the organisms that have chlorophyll and are able to produce food for them and other organisms. These autotrophs primarily need sunlight, chlorophyll and essential nutrients such as nitrogen, phosphorus, carbon, etc. to produce food and to grow. Other than the nutrients taken up from the soil there is no other means by which the autotrophs receive the nutrients. These nutrients in the soil comes after the decomposition of dead organic matter.