A function prototype can always be omitted when: A function is defined before it is first invoked. A function does not return a value. A function is invoked before it is first defined. A function takes no arguments.

A function is defined before it is first invoked.

Explanation:

A function prototype is a term in computer programming that is used as the declaration of a function that specifies function's name, parameters and return type. However, unlike function itself, which specifies what it does, a function prototype specifies function's interface only and not what it does.

Hence, A function prototype can always be omitted when: a function is defined before it is first invoked.

the answer is b) 2nd

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