Questions: Conservationists help to restore ecosystems. Which activity will positively affect the abiotic conditions of an ecosystem? A. Keeping lakes and rivers free of pollution B. Planting new trees to provide food for animals C. Monitoring the ecosystem for bacterial pathogens that can cause illness D. Mating endangered animals in captivity and restoring them to their natural habitat.

The answer is the first one (A): Keeping lakes and rivers free of pollution.

Explanation for each option:

A. Keeping lakes and rivers free of pollution - This activity directly affects the abiotic conditions of an ecosystem. Pollution can alter water chemistry, temperature, and clarity, which are all abiotic factors. By keeping these water bodies clean, conservationists help maintain the natural abiotic conditions, supporting the overall health of the ecosystem.

B. Planting new trees to provide food for animals - While this activity is beneficial for the ecosystem, it primarily affects the biotic components by providing food and habitat for animals. It does not directly impact the abiotic conditions.

C. Monitoring the ecosystem for bacterial pathogens that can cause illness - This activity is focused on the biotic aspect of the ecosystem, specifically the health of organisms within it. It does not directly influence abiotic factors.

D. Mating endangered animals in captivity and restoring them to their natural habitat - This activity is aimed at preserving and increasing the population of endangered species, which is a biotic concern. It does not directly affect the abiotic conditions of the ecosystem.

In summary, keeping lakes and rivers free of pollution is the activity that positively affects the abiotic conditions of an ecosystem.