To solve this problem, we need to understand the electronic configuration and energy levels of actinoids.$\newline$Actinoids are elements with atomic numbers from 89 (actinium) to 103 (lawrencium).$\newline$The key feature of actinoids is the filling of the 5f subshell.$\newline$Let's analyze the options:$\newline$• Option 1: Actinoid contraction refers to the gradual decrease in ionic radii across the actinoid series,$\newline$ similar to the lanthanoid contraction. This affects size but not directly the range of oxidation states.$\newline$• Option 2: The 5f, 6d, and 7s orbitals have comparable energies, allowing electrons to be removed or added$\newline$ from these subshells, resulting in a variety of oxidation states. This is the correct reason.$\newline$• Option 3: The 4f and 5d levels being close in energies is a characteristic of lanthanoids, not actinoids.$\newline$• Option 4: The radioactive nature of actinoids is a property but does not directly influence their oxidation states.$\newline$Therefore, the reason for the greater range of oxidation states in actinoids is due to the 5f, 6d, and 7s levels$\newline$having comparable energies, which corresponds to Option 2.