Final answer:
The reference to the element Rb (Rubidium) at the bottom left of a rectangle, with the lowest first ionization energy in its group, aligns with the discussed trend that ionization energy increases from left to right and from bottom to top in the periodic table.
Step-by-step explanation:
In the context of ionization energies, the supplied information pertains to the concept of successive ionization energies and its trends across the periodic table. Specifically, it suggests that for an element in the third row, as electrons are successively removed, the energy required to remove each subsequent electron increases due to the increasing electrostatic attraction between the remaining electrons and the nucleus.
Additionally, large jumps in ionization energy occur when core electrons, which are closer to the nucleus and more strongly bound, begin to be removed after valence electrons.