Which statement correctly describes the reactivity trend of Group 1 elements?

Group 1 elements, also known as alkali metals, exhibit an increasing trend in reactivity as you move down the group from lithium to cesium. This trend is primarily due to the decrease in ionization energy, which is the energy required to remove the outermost electron. As you go down the group, the outermost electron is located in a shell that is further from the nucleus. This increased distance results in a weaker electrostatic attraction between the positively charged nucleus and the negatively charged electron, making it easier for the outer electron to be removed.

Furthermore, the presence of additional electron shells increases electron shielding, which further reduces the nucleus's effective pull on the outermost electron. Consequently, the alkali metals become more reactive as you move down the group, allowing them to lose their outermost electron more easily in chemical reactions. Therefore, the statement that reactivity increases as you go down the group is accurate.