In what substance do diatoms primarily live?

Diatoms are a type of algae that primarily inhabit aquatic environments, specifically in both freshwater and saltwater ecosystems. These microscopic organisms are essential components of the aquatic food web, engaging in photosynthesis and providing oxygen and food for various marine and freshwater life forms.

In freshwater environments, diatoms can be found in rivers, lakes, and streams, while in saltwater environments, they thrive in oceans, contributing to the primary productivity of marine ecosystems. Their presence in these water bodies is crucial for ecological balance, as they serve as a foundational source of energy for higher trophic levels such as zooplankton and fish.

The other options do not accurately represent the natural habitats of diatoms. While soil may contain various types of life, it is not the primary living environment for diatoms. Air is not a suitable medium for diatoms, as they require a liquid medium for their life processes. Additionally, diatoms do not reside in human tissues; instead, they exist in water and sediment where they can receive sunlight for photosynthesis. As such, the correct response reflects their ecological niche and biological requirements.