Final answer:
Bromine (Br) has the lowest ionization energy among the given options.
Step-by-step explanation:
The element with the lowest ionization energy among the given options is bromine (Br). Ionization energy refers to the amount of energy required to remove an electron from an atom or ion. Bromine is in the halogen group, and halogens have relatively high electron affinities, meaning they have low ionization energies.