In C++ parameter passing, when you pass a variable by ________, only the current contents (a copy of the value) are sent to the receiving function.

Introduction / Context:Understanding how function arguments are passed is vital to predict whether a callee can modify a caller's data. C++ supports three common styles: pass-by-value, pass-by-reference, and pass-by-pointer. This question focuses on the style where only the data's current content is copied into the function, leaving the caller's original variable unchanged.

Given Data / Assumptions:

• The function receives either a copy of the value, a reference (alias), or a pointer (address).
• No special qualifiers like const are required to understand the basic distinction.
• Side effects on parameters are a key concern in API design and debugging.

Concept / Approach:

• By value: The callee gets its own copy; modifications affect only that copy.
• By reference: The callee receives an alias to the original, allowing direct modification.
• By pointer: The callee receives an address and can modify the pointed-to object via dereferencing.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• by reference: Passes an alias; the callee can change the caller's variable.
• globally / locally: Not parameter-passing mechanisms; they describe scope.
• None of the above: Incorrect because ”by value” is the standard term.

Common Pitfalls:

• Confusing pass-by-value with returning values by copy; these are separate operations.
• Assuming objects are always cheap to copy; use references or move semantics when appropriate.

Final Answer: