One way of which element has the lowest or highest ionization energy is by looking at the periodic table. The periodic table has many properties possible to be understood, one of which is ionization energy, which is the ability of an element to make ions, becoming more reduced (gain electrons) and making another atom become more oxidized (lose electrons), the trend of ionization energy in the periodic table follow the directions up and right, so if the atom if in the far right of the periodic table, this means that this atom has a high ionization energy, and from the given options the one with the higher ionization energy will be Fluorine, answer letter B