A CFG consists of the following components:

• A set of terminal symbols, which are the characters of the alphabet that appear in the strings generated by the grammar.
• A set of non-terminal symbols, which are placeholders for patterns of terminal symbols that can be generated by the non-terminal symbols.
• A set of productions, which are rules for replacing (or rewriting) non-terminal symbols (on the left side of the production) in a string with other non-terminal or terminal symbols (on the right side of the production).
• A start symbol, which is a special non-terminal symbol that appears in the initial string generated by the grammar.

To generate a string of terminal symbols from a CFG, we:

• Begin with a string consisting of the start symbol;
• Apply one of the productions with the start symbol on the left hand side, replacing the start symbol with the right hand side of the production;
• Repeat the process of selecting non-terminal symbols in the string, and replacing them with the right hand side of some corresponding production, until all non-terminals have been replaced by terminal symbols.

A) Context Free Grammar for if……..else………if statement

<start> ---à if ( <expr> ) <stmt> else <stmt> if ( <expr> ) <stmt>

<stmt> = Statement
<expr> = Expression
Non-terminal symbols are <stmt> and <expr>
Terminal symbols are if and else
<start> is the Start symbol

B) Context Free Grammar for Switch statement

<start> ---à switch ( <expr> ) <stmt>
<stmt> ---à case <expr> : <stmt>
<stmt> = Statement
<expr> = Expression
Non-terminal symbols are <stmt> and <expr>
Terminal symbols are switch and case
The symbol <stmt> at the end of the first line is the production
<start> is the Start symbol

C) Context Free Grammar for Do……….while statement

<start> ---à do <stmt> while ( <expr> ) ;
<stmt> = Statement
<expr> = Expression
Non-terminal symbols are <stmt> and <expr>
Terminal symbols are do and while
<start> is the Start symbol

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ANSWER 2 B