Chapter 2

1. The best approach is to implement the INotifyPropertyChanged interface, which gives you access to an event that you must raise every time a property value changes. Another supported approach is to use dependency properties, but they are harder to declare and maintain, so they should be used only when you're working with XAML controls (such as user control).
2. False. The goal of using styles is to maximize the re-use of resources, so they should be declared at the highest possible level, such as the Page container or the entire application. Even better, you can use resource dictionaries to centralize styles in a single place and organize them in a more structured way.
3. False. The default binding mode is OneWay, which means that only the target will receive notifications when the source changes and not the other way around. If you need to support two-way communication, you must set the binding mode to TwoWay.