Institution: PROBASHI KALLYAN BANK Exam: প্রবাসী কল্যাণ ব্যাংক-সিনিয়র অফিসার-09-10-2021
Topic: ICT (তথ্য ও যোগাযোগ প্রযুক্তি), Subject: Computer and ICT (তথ্য ও যোগাযোগ প্রযুক্তি)

Best Answer Explained in Below-:

Microsoft Office is classified as closed source software because its source code is proprietary and not made available to the public. This means that users cannot view, modify, or distribute the underlying code of the software. Microsoft retains control over the software's development and distribution, which is typical for closed source applications. This model allows the company to implement stringent security protocols, regular updates, and integrated customer support, all of which contribute to a more stable and reliable user experience.

In contrast, open source software allows users to access and modify the code, fostering collaboration and community-driven improvements. The other options listed—horizontal market software and vertical market software—refer to the target market of the application rather than its licensing model. Horizontal market software is designed for a broad audience and common business functions, while vertical market software is specialized for specific industries. Microsoft Office primarily serves a wide range of tasks across multiple sectors but remains fundamentally closed source, making option A the correct answer.