Final answer:
The size of an array in C can be increased using the realloc() function, which allows a program to change the size of a previously allocated memory block. This should be done with caution to avoid memory issues. Functions like resize(), increase(), and expand() are not standard C functions for this purpose.
Step-by-step explanation:
In programming, specifically in the context of the C language, the size of an array can be increased using the realloc() function. This stands for 'reallocate memory', and it allows a program to change the size of a previously allocated memory block to a new size. If you have an array created with dynamic memory allocation (using malloc or calloc), you can use realloc() to change its size. However, this should be done with caution as it can lead to memory leaks or data corruption if not handled correctly. It's important to note that the resize(), increase(), and expand() functions mentioned in the question are not standard functions in C for altering the size of an array.
If the array is declared to have a fixed size, then it cannot be resized during runtime. In such cases, programmers typically create a new, larger array and copy the contents of the original array into the new one. The concept of automatically resizing arrays by a certain factor, such as by two, four, six, or eight, is not inherently a feature of arrays in C but could be part of a custom implementation of dynamic arrays.