Which concept of grammar is used in the compiler?a) Lexical analysis b) Parser c) Code generation d) Code optimization

The concept of grammar used in the compiler is b) Parser.

Here's a step-by-step explanation:

1. Lexical Analysis: This is the first phase of a compiler. It converts the High Level input program into a sequence of Tokens.

2. Parser: This is the second phase of a compiler. It takes the token produced by lexical analysis as input and generates a parse tree (or syntax tree). In this phase, token arrangements are checked against the source code's grammatical structure.

3. Code Generation: This is the phase where the parse tree or the intermediate code is converted into the target machine code.

4. Code Optimization: This is the phase where the compiler tries to improve the machine code to make it faster and take up less space.

So, the concept of grammar is used in the Parser phase where the grammatical structure of the source code is checked.