Questions

The primary tool used in structured design is a structure chart.

It's important here to focus on the word "implemented". "There's nothing wrong with having a thousand great ideas, but if the only place they live is on your notepad what's the point? Better still you need a good ending. If your previous company took your advice and ended up going bankrupt, that's not such a great example either.Be prepared with a story about an idea of yours that was taken from idea to implementation and considered successful.

C++ is not an Operating System.

An Operating System is a collection of system programs that manages all the other programs application programs in a computer as well as the allocation and use of hardware resources such as the CPU, Memory and the Hard Disk Drive.

It acts as an interface between the hardware and the user level program.

It controls and facilitates the overall operation of a computer. 

Here

UNIX : UNIX is a popular multi-user, multitasking operating system (OS) developed at Bell Labs.

Windows NT : Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993.

DOS : DOS is Disk Operating System. The term DOS can refer to any operating system.

C++ : C++ is a programming language and computing platform.

Hence, C++ is not an Operating System.