Which file do you modify to add platform-specific dependencies in a Flutter project?

To add platform-specific dependencies in a Flutter project, you modify the 'pubspec.yaml' file. This file is the central configuration file for Flutter projects and includes information about the project's name, dependencies, and assets. By specifying platform-specific dependencies in the 'pubspec.yaml' file, Flutter ensures the correct packages are included when building for different platforms. Familiarity with 'pubspec.yaml' is essential for managing project dependencies effectively.