The correct answer is A. Freshwater ponds.
Volvox is a genus of green algae that is found in freshwater ponds and lakes. It is a colonial organism, meaning that it is made up of many individual cells that live together in a single colony. The cells in a Volvox colony are connected by cytoplasmic bridges, which allow them to share nutrients and information. Volvox colonies are typically spherical in shape, and they can range in size from a few millimeters to a few centimeters in diameter.
Volvox colonies are photosynthetic, meaning that they can produce their own food using sunlight. They are also motile, meaning that they can move around by using flagella. Volvox colonies are an important part of the freshwater ecosystem, and they are a food source for many animals, including fish, frogs, and insects.
Option B, salt lakes, is incorrect because Volvox colonies are not found in salt water. Salt water is too salty for Volvox cells to survive.
Option C, seawater, is incorrect for the same reason as option B. Seawater is too salty for Volvox cells to survive.
Option D, spring, is incorrect because Volvox colonies are not found in springs. Springs are typically too cold for Volvox cells to survive.