Final answer:
Among the given elements, Oxygen (O) has the highest first ionization energy due to its position furthest to the right and topmost in the periodic table.
Step-by-step explanation:
The question revolves around the concept of ionization energy, which is the energy required to remove the most loosely bound electron from an isolated gaseous atom. To determine which of the given elements - Pb (Lead), C (Carbon), O (Oxygen), Se (Selenium) - has the highest ionization energy, one must consider their positions on the periodic table. Generally, ionization energy increases across a period (from left to right) and decreases down a group (from top to bottom).
Given the options, Oxygen (O) is the element positioned farthest to the right and at the top among the other elements listed, indicating that it would have the highest first ionization energy.