Final answer:
b. Leaching and runoff are the major causes of nutrient loss from terrestrial ecosystems, with significant impacts on soil fertility and water quality.
Step-by-step explanation:
A major cause of nutrient loss from most terrestrial ecosystems is b. leaching and runoff. Leaching is the process by which nutrients are lost from the soil as water percolates through it, carrying these nutrients away from the root zone where plants can absorb them.
Runoff occurs when rainwater or melted snow flows over the land's surface and carries away soil particles and nutrients, which can eventually lead to bodies of water, causing issues like eutrophication.
The loss of nutrients via leaching and runoff is significant because it can deplete the soil of essential elements required for plant growth, potentially leading to diminished productivity in the ecosystem and contributing to problems such as water pollution and harmful algal blooms.