Answer: Option (d) is the correct answer.
Explanation:
An orbital is defined as the energy shell which can contain a maximum of two electrons with opposite spins.
A wave like behavior of an electron is determined by an orbital and basically an orbital acts like a mathematical function.
For example, in a p-sub shell the orbitals present are [tex]p_{x}[/tex], [tex]p_{y}[/tex] and [tex]p_{z}[/tex].
Therefore, we can conclude that orbitals are defined by energy level.
