Final answer:
To use the rand() function, D) cstdlib header file must be included in the program. cstdlib allows access to various functions, including the rand() function for generating random numbers. The correct option is D) cstdlib.
Step-by-step explanation:
To use the rand() function in C or C++ programs, you must include the header file . So, the correct answer is D) cstdlib. The rand() function is used to generate random numbers in a program, and including the cstdlib header is necessary to use this function and other standard library functions such as malloc, free, system, and more.
To employ the rand() function in C++, inclusion of the cstdlib header file is imperative. This file provides essential declarations for random number generation and memory allocation functions.
By incorporating cstdlib, the program gains access to the rand() function, allowing the generation of pseudo-random integers within specified ranges.
An example usage involves seeding the random number generator with std::time(nullptr) to introduce variability. The generated random numbers find applications in diverse scenarios, from simulations to games. In summary, including cstdlib ensures the availability of necessary functionalities for effective utilization of the rand() function in C++ programming
The correct option is D) cstdlib.