Answer:
Option (D)
Step-by-step explanation:
Organic detritus usually refers to those materials that are the remains of dead organisms such as plants and animals.
The flowing water ecosystem such as the head-water streams obtains most of the materials from the nearby terrestrial and aquatic places due to the surface runoff. It is highly rich in the amount of organic detritus, as the materials such as leaves, branches, roots, soil particles, and other organic waste products are transported from the land areas, thereby obtains its energy from them.
Thus, the correct answer is option (D).