As the ionization energies of the elements decreases down the group carbon has got the highest ionization energy in the group being at the top of the group.
Carbon is on the top of the group 4 among the given elements. Hence, Carbon has the highest ionization energy.
In a brief, the system software is the interface between the hardware and user applications. System software is a type of computer program that is designed to run a computer’s hardware and application programs.
Examples : OS, System utilities, BIOS like mouse, keyboard, hard disc, Device drivers, Assembler,...