The "Object Spy" feature is unique to QTP (Quick Test Professional). It allows testers to point and click on application objects to view their properties, making it easier to identify and understand the attributes of various application components. This aids in creating accurate and effective test scripts.

White-box testing, also known as Structural testing, emphasizes examining the internal structures and workings of an application. This is in contrast to black-box testing which focuses solely on the software's outputs in response to certain inputs, ignoring its internal mechanisms.

Connectivity testing is essential for apps that may function differently under various network conditions. In this case, the app's performance on mobile data versus Wi-Fi can be assessed under different conditions to ensure consistent user experience. Other testing types, while valuable, may not directly diagnose this specific issue.

System testing is a level of testing where the complete system is tested as a whole. Thus, it should be prioritized when the complete system is ready for testing. This level of testing comes after integration testing and focuses on evaluating the system's compliance with the specified requirements. While unit tests evaluate individual components and integration tests ensure that those components interact well, system testing verifies that the entire system meets the desired specifications and functionalities.

In the error guessing technique, testers leverage their experience and intuition to predict where errors might be present. They often create an "Error Profile," which is a list or description of familiar errors or issues they've encountered in similar situations before. This helps streamline the testing process and targets specific areas that are prone to defects.

"Loop Testing" is a white-box testing technique that specifically focuses on validating all loops in the software application. This ensures that loops function as expected under all possible conditions and iterations.

Stress Testing involves assessing the system under extreme conditions beyond its specifications. In scenarios where there's an unexpected surge in users, like company-wide events, it's vital to determine if the software can sustain the stress or if it breaks, thus helping in predicting and preventing potential crashes.

The Agile model of Software Development Life Cycle (SDLC) emphasizes continuous iterations of development and testing. Each iteration involves phases like requirements, design, coding, and testing.

Cloud-based mobile application testing offers scalable testing environments, meaning you can expand or reduce resources as per your testing needs. This scalability ensures flexibility and cost-effectiveness, allowing teams to test on multiple devices and configurations without the need for physical infrastructure, unlike traditional labs. Moreover, cloud-based testing isn't bound by geographic locations, ensuring wider test coverage.

Jenkins is a powerful and widely-used open-source tool that provides continuous integration and continuous delivery facilities for software development. Its extensive plugin system and integrations allow it to fit seamlessly into a DevOps environment, enabling automatic code integration, testing, and deployment processes.