What is the difference between `MutableLiveData` and `LiveData`?

The distinction between MutableLiveData and LiveData primarily revolves around mutability. MutableLiveData is a subclass of LiveData that allows for changes in its data. This means you can use MutableLiveData to update its value programmatically within your code, making it suitable for scenarios where data needs to change over time. It's often used in ViewModels to manage UI-related data in a lifecycle-conscious way.

On the other hand, LiveData is designed to be read-only from a consumer's perspective, meaning that if you provide a LiveData instance, other classes can observe it but cannot modify its value directly. This encapsulation enforces a clear separation of concerns, ensuring that only the class that owns the data (like a ViewModel) can change its values, thus providing better control over the data flow and preventing unintended modifications from outside sources.

The other options do not accurately reflect the main functional differences in terms of mutability or usage context, making option A the most relevant and accurate choice regarding the nature of both MutableLiveData and LiveData.