Answer : Option A) carbon
Explanation : In group 4 A carbon has got the highest ionization energy amongst the given choices. 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.
The ionization energy (Ei) can be defined as the amount of energy which is required to remove the most loosely bound electron, which is the valence electron, of an isolated gaseous atom to form a cation.