Final answer:
The fourth main energy level has a total of 16 orbitals, which can hold up to 32 electrons.
Step-by-step explanation:
The student asked about the total number of orbitals in the fourth main energy level. In chemistry, orbitals are regions around the nucleus of an atom where electrons are likely to be found. The fourth energy level has 16 orbitals in total. This includes one s orbital, three p orbitals, five d orbitals, and seven f orbitals. Since each orbital can hold a maximum of two electrons, the fourth energy level can hold up to 32 electrons. Therefore, the correct answer is D. 16.