Institution: AGRANI BANK LTD Exam: Agrani bank Ltd - Officer 04.07.2008
Topic: ICT (তথ্য ও যোগাযোগ প্রযুক্তি), Subject: Computer and ICT (তথ্য ও যোগাযোগ প্রযুক্তি)

Best Answer Explained in Below-:

An operating system (OS) is a crucial software component that manages computer hardware and software resources, providing services for computer programs. Among the options given:

A) **Oracle** refers to a database management system (DBMS), primarily designed for managing and storing data rather than serving as an interface between users and the hardware.

B) **PowerPoint** is a presentation software application used for creating slideshow presentations. It does not manage hardware or provide a platform for running applications, which is the primary role of an operating system.

C) **Unix**, on the other hand, is a well-known operating system developed in the 1960s and 1970s. It provides a multiuser environment, supports multitasking, and manages resources such as memory and processors efficiently. Unix has laid the groundwork for many modern operating systems, including Linux and macOS, highlighting its foundational role in the development of computing.

D) **Excel** is a spreadsheet application used for data analysis and visualization. Like PowerPoint, it does not fulfill the functions of an operating system.

In conclusion, the only option that qualifies as an operating system is C) Unix, making it the correct answer.