Tierra is the marketer for Far West Imports. They're the project lead for a new smartphone app that will help customers to order products more easily. Thanks to Google's advice, their dev team has incorporated many features to boost conversion numbers. The marketing VP is insisting that Tierra assess the efficiency of the shopping basket and checkout features. Which Google service allows them to test the app's UI and features?

Firebase A/B Testing is the correct answer because it is a Google service specifically designed for testing UI and features within mobile applications, allowing marketers to run experiments and optimize the user experience. SplitMetrics and Optimizely are also A/B testing platforms, but they are not Google services. SplitMetrics focuses on app store optimization, and Optimizely is a broader experimentation platform. Google Analytics 360 is an analytics service for tracking user behavior, not for directly conducting A/B tests on app features.