In Android, how can your application perform actions such as sending an email by reusing functionality provided by other installed applications?

Introduction / Context:
Android encourages applications to share functionality by delegating certain tasks to other installed apps. Sending an email is a classic example: instead of building your own mail client, you can request that a mail app handle the action. This question tests whether you understand how implicit Intents enable this reuse of capabilities in a secure and user friendly way.

Given Data / Assumptions:

• The application wants to perform an action such as sending email or sharing text.
• Other installed applications already provide this functionality.
• Android uses Intents as a communication mechanism between components.

Concept / Approach:
Implicit Intents specify an action to perform without naming a specific target component. For example, ACTION_SEND or ACTION_VIEW describes a general operation. The system Intent resolver matches this Intent against all Activities that declare compatible intent filters in their manifests. The user can then choose which application to use if more than one matches. This pattern lets your app offload work like sending email to specialized apps while keeping permissions and responsibilities clearly separated.

Step-by-Step Solution:
Step 1: Construct an Intent with an action such as ACTION_SEND and include extras like email address, subject, and body.Step 2: Set the MIME type appropriately, for example text/plain for a simple message.Step 3: Call startActivity with Intent.createChooser so that the user can pick an installed email or messaging application.Step 4: The system presents a chooser dialog listing apps that can handle the Intent based on their declared intent filters.Step 5: The selected application opens with the email populated, allowing the user to review and send it. This process is exactly what option A describes.

Verification / Alternative check:
Android documentation and sample code show sharing patterns that use implicit Intents instead of tight coupling. They do not recommend copying code from other apps or modifying manifests at runtime. Testing on a real device further confirms that ACTION_SEND Intents launch appropriate email or messaging clients chosen by the user.

Why Other Options Are Wrong:
Option B is incorrect because applications are packaged separately and copying code from other apps is not supported or legal in normal development. Option C is wrong since AndroidManifest.xml is not editable at runtime and cannot be used to inject code into other apps. Option D is invalid because subclassing Activity from another app package does not cause your code to run inside that app, and package boundaries remain enforced by the system.

Common Pitfalls:
Developers sometimes hard code a particular email package name, which reduces flexibility and may break if that app is not installed. Another mistake is forgetting to handle the case where no email capable application is present. Using implicit Intents and graceful fallback logic ensures that your application degrades nicely while maintaining a good user experience.

Final Answer:
By using Intents, for example an implicit Intent with ACTION_SEND that the system resolves to an appropriate email application.