What Android ViewGroup arranges child views in a single horizontal or vertical row?

The ViewGroup in Android that arranges its child views in a single horizontal or vertical row is the LinearLayout.

The provided XML snippet demonstrates this:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <!-- Add child views here -->
</LinearLayout>

The android:orientation attribute can be set to either "horizontal" or "vertical" to define how child views are arranged.

The answer is: LinearLayout