Water quality has been declining worldwide.. Which strategy will best maintain water quality? A. Catch rainfall in barrels B. Clear land of dead vegetation C. Store water in reservoirs D. Use fewer toxic chemicals

## Step 1
The problem is asking us to identify the best strategy to maintain water quality. Each option provided has a different impact on water quality.

## Step 2
Option A, "Catch rainfall in barrels", is a method of rainwater harvesting. This can help in reducing the demand on freshwater sources, but it does not directly improve water quality.

## Step 3
Option B, "Clear land of dead vegetation", can actually degrade water quality. Dead vegetation can act as a natural filter for water, and removing it can lead to increased runoff and erosion, which can carry pollutants into water bodies.

## Step 4
Option C, "Store water in reservoirs", can help in managing water supply but does not inherently improve water quality. Reservoirs can sometimes lead to issues like eutrophication if they retain water for long periods.

## Step 5
Option D, "Use fewer toxic chemicals", directly addresses the issue of water quality. Reducing the use of toxic chemicals in agriculture, industry, and households can significantly decrease the amount of pollutants entering water bodies, thereby maintaining or improving water quality.