Final answer:
Scientists working for a water district primarily analyze water composition, manage water supply and sanitation, and understand water resource management. They use their knowledge to ensure the suitability of water for intended uses and monitor essential variables like well water levels.
Step-by-step explanation:
Scientists working for a water district primarily analyze water composition. They are involved in ensuring that water is drinkable, which includes engineering solutions related to water supply and sanitation, and the management of water treatment and distribution systems.
They work to understand the complexity of water use and water resources management, which encompasses human consumption, food production, and energy production through projects such as dams for hydroelectric power. Civil engineers also monitor water systems to measure variables like well water levels to inform water management strategies.
It is also crucial for such scientists to understand the science underlying various techniques for providing water supply, as this knowledge enables exploring a wide range of approaches. Furthermore, water engineers do not strictly need a background in biology but should have knowledge of physical, chemical, and biological aspects of water to ensure its suitability for intended uses, such as public water supply and the protection of ecosystems.
Therefore answer is A) analyze water composition.