It's often Linux since Linux is free, but it could be Windows.
Answer:
constant or constant expression
register name
variable name (memory)
Explanation:
Literally, operand means data which an operation can be performed on. The operation could be an arithmetic or logical operation.
From the list of options, several operations can be performed on:
- constants e.g.

- registers and
- variables e.g. (a + b)
<em>However, no operation can be performed on keywords and/or reserved words.</em>
Answer:
All of the above.
Explanation:
API is an acronym for application programming interface and it can be defined as a software intermediary (computing interface) comprising of sets of codes, tools and protocols that helps software applications and the computer to communicate with each other, as well enable the exchange of data. Some examples of popular APIs are Go-ogle, Face-book, Twitter etc.
The main characteristics and functions of an application programming interface (API) includes;
I. Allows different devices to connect with each other.
II. Allows for Interactivity between devices and software.
III. Messenger program that takes requests and delivers the response back to the user.
IV. Allows the creation of applications that access the features or data of an operating system, application, or other services.
V. Specifies how software components should interact.
VI. Used when programming graphical user interface (GUI) components
SpongeBob, Teen Titan Go, Future Worm. That's all I can think!