In the C++ standard library, which header should you include to use the generic std::min and std::max functions?

Introduction / Context:
The C++ standard library provides many ready made utility functions, including std::min and std::max for finding the smaller or larger of two values. These functions live in specific headers, and including the correct header is important for clean, portable code. This question checks whether you know which header file you should include to access std::min and std::max in modern C++ programs.

Given Data / Assumptions:

• We are writing standard conforming C++ code.
• We want to use the generic std::min and std::max function templates.
• We know that different standard library facilities are split across different headers, such as <iostream>, <string>, and <algorithm>.
• We are not relying on non standard extensions or implicit declarations.

Concept / Approach:
The header <algorithm> in C++ groups a large set of generic algorithms that operate on ranges, such as std::sort, std::find, and std::for_each. The std::min and std::max functions, along with overloads and related templates such as std::min_element and std::max_element, are also part of this header. While some older code may rely on incidental declarations pulled in through other headers, best practice and the standard specification require including <algorithm> when you use these functions. Therefore, the correct option should identify <algorithm> as the defining header.

Step-by-Step Solution:
Step 1: Recall that the C++ standard library divides functionality into logical headers such as <iostream>, <string>, and <algorithm>. Step 2: Remember that <iostream> provides input and output streams like std::cin and std::cout, not general algorithms. Step 3: Note that <string> defines the std::string class and related operations, but it does not define generic min or max functions for arbitrary types. Step 4: Recognise that <algorithm> is where the standard places generic algorithms, including std::min and std::max. Step 5: Select option c, which correctly names <algorithm> as the header that declares std::min and std::max.

Verification / Alternative check:
If you inspect the C++ standard or standard library documentation for std::min and std::max, you will see that the synopsis for these functions appears under the <algorithm> header. Compilers may still compile code where another header happens to include <algorithm> internally, but that behaviour is not guaranteed by the standard. Writing #include <algorithm> before using std::min or std::max ensures consistent behaviour across compilers and platforms.

Why Other Options Are Wrong:
Option a, <iostream>, focuses on input and output streams and does not formally introduce std::min or std::max. Option b, <string>, defines std::string and related utilities but is not responsible for the general min and max templates. Option d is incorrect because std::min and std::max are library functions, not built in language keywords, and they require the appropriate header for proper declaration and use.

Common Pitfalls:
A common pitfall is relying on indirect header inclusion, where one header happens to pull in another. This can cause code to compile on one implementation but fail on another where the internal structure of headers differs. Another mistake is assuming that all standard library facilities are available after including <iostream>, which is not the case. For clean, portable interview quality code, always include the specific header that declares the functions you use, such as <algorithm> for std::min and std::max.

Final Answer:
You should include the <algorithm> header, which declares std::min, std::max, and many other generic algorithms when you want to use these functions.