Why is an ASP.NET-Core app 'Configuration/AppSettings' POCO passed around as IOptions instead of just T?

Question

With .NET-Core apps the configuration data read from some file/environment is loaded into an IConfigurationRoot instance. But I keep seeing examples that show that the injected instance is an IOptions<T> .. not an IConfigurationRoot.

• Why IOptions?
• What is the advantage of this class instead of just having my own AppSettings POCO?
• Do I need to do it this way? Is there another way?

For example..

public static IConfigurationRoot Configuration { get; set; }

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder().SetBasePath(env.ContentRootPath)
                                            .AddJsonFile("appSettings.json", true, true)
                                            .AddJsonFile($"appSettings.{env.EnvironmentName}.json", true)
                                            .AddEnvironmentVariables();
    Configuration = builder.Build();
}

public void ConfigureServices(IServiceCollection services)
{
    // Register the IConfiguration instance which MyOptions binds against.
    services.Configure<AppConfiguration>(Configuration);

    // <snip other stuff>
}

public AccountController(IOptions<AppConfiguration> appConfiguration)
{
    // do stuff with appConfiguration here.
}