Question: You need to upgrade to the latest version of the Android Gradle plugin. Which file should you modify?

1. root_project_dir/app/build.gradle.
2. root_project_dir/settings.gradle.
3. root_project_dir/build.gradle.
4. root_project_dir/app/gradle.properties.

Answer: The correct answer of the above question is Option C:root_project_dir/build.gradle.