Final answer:
Sodium (Na) requires the least amount of energy to remove the most loosely held electron.
Step-by-step explanation:
To determine which element requires the least amount of energy to remove the most loosely held electron, we must consider ionization energy. Ionization energy is the energy required to remove an electron from an atom. In this case, the element with the smallest ionization energy would require the least amount of energy to remove the most loosely held electron.
Based on the given options, the element that has the smallest ionization energy is sodium (Na). Sodium is in Group 1 of the periodic table, which means it has a single, loosely held electron in its outermost energy level. This electron can be easily removed, resulting in a low ionization energy.