Final answer:
California's rice fields are visited by migrating waterfowl.
Step-by-step explanation:
The correct answer is a. visited by migrating waterfowl. California's rice fields are visited by migrating waterfowl. The fields provide an important food source for many species of waterfowl, such as ducks and geese, during their migration. The flooded rice fields offer abundant food and nesting opportunities for these birds.