In Android application development, what is the main reason for using a defined process lifecycle for activities and applications?

Introduction / Context:
Android is designed for mobile devices that have limited memory and battery resources. To handle many applications at once, Android uses a process and activity lifecycle model. This model defines states such as created, started, resumed, paused, stopped, and destroyed. This question asks why such a lifecycle is important and what main goal it serves.

Given Data / Assumptions:

• We are working in the context of Android applications.
• Activities and processes can move between foreground, background, and stopped states.
• The operating system must balance user experience with resource limitations.
• We want the primary reason for having a lifecycle model.

Concept / Approach:
The Android lifecycle allows the system to reclaim resources from processes that are in the background or no longer needed, while keeping the current activity responsive. Developers implement callback methods such as onPause, onStop, and onDestroy to save state and release resources. The correct option must mention both efficient resource management and maintaining a smooth user experience as activities change state.

Step-by-Step Solution:
1. Recall that Android may kill background processes when memory is low, relying on lifecycle callbacks to allow applications to save state.2. This behaviour lets the system run many applications while still keeping the current one responsive.3. Option A states that the lifecycle is used to manage memory and resources efficiently while providing a smooth user experience as activities move between states. This aligns with Android design goals.4. Option B suggests that all applications should always run at full CPU usage, which would quickly drain the battery and make the device unusable.5. Option C claims the goal is to disable background processes entirely, which is incorrect because many apps need background services for notifications and syncing.6. Option D says the lifecycle prevents the system from stopping processes when resources are low, which contradicts actual Android behaviour where low priority processes can be killed.7. Therefore, Option A is the correct answer.

Verification / Alternative check:
Android developer documentation emphasises that the lifecycle allows the system to manage resources proactively. For example, when an activity goes into the background, onPause and onStop are called so you can release camera, network, or sensor resources. If the system later kills the process, the user can still return to the activity and see state restored. This balance between resource management and user experience confirms the explanation in Option A.

Why Other Options Are Wrong:
Option B is wrong because constant full CPU usage would waste power and degrade performance.Option C is wrong because Android supports background services and notifications as part of normal use, not as an exception.Option D is wrong because Android explicitly can stop processes to reclaim memory, and lifecycle design supports that ability.

Common Pitfalls:
New Android developers sometimes ignore lifecycle callbacks and keep heavy resources like network connections or media players active even when an activity is not visible, leading to battery drain and crashes. Another pitfall is assuming that activities will never be destroyed, which results in lost data when the system reclaims memory. Understanding the lifecycle and its purpose is essential for building stable and efficient apps.

Final Answer:
To manage memory and resources efficiently while providing a smooth user experience as activities move between states.