The correct answer is:
(d) Arising of compiler warnings & Unchecked behavior on program
Explanation: In C++, when you use iterators without proper type checking, it can lead to unchecked behavior in the program, which means that there may be type mismatches or invalid operations being performed on the iterated elements. Additionally, many modern compilers will issue warnings to alert the programmer about potential issues, such as when the iterator type does not match the expected type.
Thus, both compiler warnings and the possibility of unchecked behavior in the program can arise when iterators are unchecked.