Cannot find Prism.PrismApplication - prism

Question

I just started my first WPF app using MVVMLight, PRISM, and DryIoc. The App.xaml refers to prism:PrismApplication as described in https://prismlibrary.com/docs/wpf/getting-started.html without error.
<prism:PrismApplication x:Class="DYC.MembershipAndDues.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:DYC.MembershipAndDues"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:prism="http://prismlibrary.com/"
xmlns:vm="clr-namespace:DYC.MembershipAndDues.ViewModel"
xmlns:d1p1="http://schemas.openxmlformats.org/markup-compatibility/2006"
d1p1:Ignorable="d"
DispatcherUnhandledException="Application_DispatcherUnhandledException">
<Application.Resources>
<ResourceDictionary>
<vm:ViewModelLocator x:Key="Locator" d:IsDataSource="True" />
</ResourceDictionary>
</Application.Resources>
</prism:PrismApplication>
In the App.xaml.cs, Prism.PrismApplication cannot be found. I found PrismApplicationBase in the object explorer, which works for App.xaml.cs, but in App.xaml, prism:PrismApplicationBase cannot be found. There appears to be a disconnect between the xaml declaration at xmlns:prism="http://prismlibrary.com/" and the packages that I have loaded.
<?xml version="1.0" encoding="utf-8"?>
<packages>
<package id="CommonServiceLocator" version="2.0.5" targetFramework="net472" />
<package id="DryIoc.dll" version="4.0.7" targetFramework="net472" />
<package id="MvvmLight" version="5.4.1.1" targetFramework="net472" />
<package id="MvvmLightLibs" version="5.4.1.1" targetFramework="net472" />
<package id="Prism.Core" version="7.2.0.1422" targetFramework="net472" />
<package id="Prism.DryIoc" version="7.2.0.1422" targetFramework="net472" />
<package id="Prism.Wpf" version="7.2.0.1422" targetFramework="net472" />
<package id="System.ValueTuple" version="4.5.0" targetFramework="net472" />
</packages>
What am I missing?

Answer 1

Found it! It's included in the dependancy injector container, i.e. Prism.DryIoc or Prism.Unity depending on which container you are using.