The application is described as being designed for a PC browser and not functioning well on mobile devices. This is the defining characteristic of a traditional browser-based application that lacks responsive or adaptive design. Such applications are built for the screen real estate, resolution, and input methods (keyboard/mouse) of a personal computer. In contrast, mobile web applications and sites are specifically designed and optimized for the constraints and features of mobile devices, ensuring they function correctly on smaller, touch-based screens.

A. Native Mobile Application: This type of application is installed directly onto the mobile device's operating system and is not accessed through a browser.

C. Mobile Web Application: This is a web application specifically optimized to look and feel like a native app and function well within a mobile browser.

D. Mobile Web Site: This is a version of a website that is specifically designed and optimized for viewing and interaction on a mobile device's browser.

1. ISTQB® Certified Tester Mobile Application Testing Syllabus (CT-MAT), Version 2019.

Section 1.2.2, Mobile Web Applications: This section defines mobile web applications as those "accessed using a mobile browser" and designed for mobile platforms. This implicitly defines a traditional web application as one not designed for mobile, which would therefore "not function well when accessed from a mobile device." The syllabus distinguishes between applications designed for mobile versus those that are not.

2. ISTQB® Certified Tester Advanced Level Syllabus Technical Test Analyst (CTAL-TTA), Version 2019.

Section 2.3.1, General Architectural Considerations: This section discusses different software architectures. While not naming "traditional browser-based application" explicitly, it describes multi-tier architectures (e.g., client-server) where the client is a web browser. The failure to function on a mobile device is a quality characteristic (usability, compatibility) issue for such an architecture if it hasn't been designed to be responsive.

3. CS50's Web Programming with Python and JavaScript, Harvard University.

Lecture on Responsive Design: This courseware explains that traditional websites were designed for fixed-width desktop screens. Without responsive design principles (using media queries, flexible grids), these sites render poorly on mobile devices, matching the scenario in the question. A "traditional browser-based application" is one that predates or ignores responsive design.