If a language supports an implicit variable declaration, does it mean that the language is dynamically typed? If not, prove that an implicit variable declaration does not mean that a language is dynamically typed.

Assume that the below statement is written in C. What is a value that variable testVar has? (Assume that it uses C with the version that supports Boolean values.)

int testVar = 15 + b + true;

Before C was developed, assembly language was usually used to write operating systems because of its fast performance. But now, in most cases, C is used to write operating systems. Explain why C is popularly used in the operating system instead of assembly language.