Stored Procedures and stored function are the same, except
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Stored function returns a value and a stored procedure does not.
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Stored procedure returns a value and a stored function does not.
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Stored function returns a value and a stored procedure may OR may not.
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Stored procedure returns a value and a stored function may OR may not.
The fundamental difference is that a stored function MUST return a single value, while a stored procedure does NOT return a value (it can have OUT parameters but no RETURN statement). Option A captures this precisely. Option C is misleading because stored functions always return a value - they cannot optionally return or not return.
The defining difference between a stored function and a stored procedure in PL/SQL is that a function is required to return a single value via a RETURN statement, while a procedure has no such requirement and typically communicates results (if any) through OUT parameters instead. This is why 'stored function returns a value and a stored procedure does not' correctly captures the distinction.