Multiple choice chmod() function is defined in which header file? assert.h dos.h io.h mem.h Reveal answer Fill a bubble to check yourself C Correct answer Explanation chmod() is used to change file permissions (mode). In DOS-based C compilers like Turbo C, this function is declared in io.h. In Unix systems, it would be in sys/stat.h, but io.h is the correct answer for the DOS/Windows context.