Question

where would you expect to find the highest amount of dissolved materials, pollution, and nutrients along a rivers run? in the middle at the beginning at the mouth, near the ocean the same all along the river

Explanation:

Step1: River flow characteristics

As a river flows from its source (beginning) to its mouth (near the ocean), it picks up various substances.

Step2: Accumulation of materials

Along its course, it collects dissolved materials, pollution (from human activities, industrial waste etc. along its banks) and nutrients (from soil erosion, agricultural runoff etc.). By the time it reaches the mouth, near the ocean, all these substances have accumulated. So the highest amount of dissolved materials, pollution and nutrients is at the mouth near the ocean.

Answer:

C. at the mouth, near the ocean