Why “C” language mostly preferred than assembly language?

Answer:

C helps programmers focus on the structure of the code rather than the low-level demands of the CPU. They can organize code into components, such as functions and files and they have ways of managing the complexity of a project; without thinking about the nitty-gritty of issues such as how function calls work.

Since C is a portable language, code can be organized into general-purpose libraries that can be used on any platform, often with no modification. It is a great weapon against ‘reinventing the wheel.