To dynamically load a component at runtime based on user actions, you would typically use the Dynamic Component Loader (e.g., ViewContainerRef.createComponent) or ngIf with TemplateRefs. This allows you to load components dynamically into the view. While Angular Modules and NgModule Factories are relevant to Angular's architecture, they are not directly used for dynamic component loading. Dependency Injection and Service Providers are used for managing dependencies, not dynamic component loading. Event Emitters and ngTemplateOutlet are not the primary tools for this specific task.

Angular's *ngFor directive is used to repeat a portion of the DOM tree for each item in a list. It's commonly used for rendering lists of items, iterating over arrays, and displaying dynamic content based on data.

To make a service optional for injection in a component in Angular (or similar frameworks), you can use the "@Optional" decorator when injecting the service. This indicates that the service is not required, and if it's not available, the injection will not result in an error. The other options are not valid methods for making a service optional.

In Angular's Reactive Forms, the FormBuilder is a service that provides convenient methods to construct form controls. It simplifies the process of creating and managing form controls and their corresponding form groups. Using FormBuilder, developers can easily define form structures with various input types and validation rules.

In Angular's hierarchical dependency injection system, the root injector is the first injector that is checked when trying to resolve a service dependency. The root injector provides a global scope for services, and if the service is not found there, Angular will progressively look for it in other injectors further down the hierarchy. Understanding this hierarchy is essential for managing service dependencies in Angular applications.

In Angular, the directive used to link to routes is routerLink. This directive is used in templates to generate hyperlinks that navigate to different views or components in an Angular application when clicked. The other options are not valid Angular directives for routing purposes.

To transform each value emitted by an Observable, you use the map operator. The map operator applies a given project function to each value emitted by the source Observable and emits the transformed values. It's a fundamental operator for data transformation in RxJS.

To pass matrix parameters in a route in Angular, you can use the ;param syntax in the router link. Matrix parameters are often used to represent additional data associated with a route, and this syntax allows you to specify them in the URL. For example, /route;param=value would pass a matrix parameter named "param" with the value "value" to the route.

The Angular Route Guard 'CanLoad' is used to determine if a route can even be loaded. This guard checks conditions before loading the entire module associated with the route, making it useful for scenarios where you want to prevent loading a module or route based on certain conditions, such as authentication or feature flags. The other guards are used for different purposes, like 'CanActivate' for allowing or denying access to a route, 'CanActivateChild' for child routes, and 'CanDeactivate' for confirming navigation away from a component.

The Default change detection strategy checks the component and its children every time something might have changed, regardless of the origin of the change. This strategy can be less efficient than the OnPush strategy, which selectively checks components based on their input changes. Understanding these strategies is crucial for optimizing Angular applications.