Final answer:
The second principal energy level contains two energy sublevels: one s orbital and three p orbitals, which are categorized as the 2s and 2p sublevels.
Step-by-step explanation:
The second principal energy level contains two energy sublevels: the 2s and 2p sublevels. Within the second energy level, there is one s orbital and three p orbitals, making up the two sublevels.
The s orbital is filled first because it is at a lower energy, following the Aufbau principle that states electrons fill orbitals starting from the lowest available energy. Thus, the correct answer to the question is Option b. 2.