A, B, C, harder than 1, 2, 3

What this C++ type-deduction interview question tests

This is an easy C++ question that probes your understanding of type deduction rules in modern C++ (C++17 and beyond). It appears frequently in coding interviews because getting types right is foundational to writing correct, efficient code — and because type deduction can be surprisingly subtle in practice.

To solve questions like this, you need to mentally trace through the compiler's type-deduction algorithm: how does the declared type of a variable interact with the type of its initializer? What role do qualifiers, references, and template argument deduction play? The question rewards precision and systematic thinking over guesswork.

• Template argument deduction rules
• Qualifiers (const, volatile, reference) and their handling during deduction
• How initializer expressions affect the final type