The correct answer is: Azimuthal quantum number.
The azimuthal quantum number, $l$, determines the shape of an atomic orbital. It can have values from 0 to $n-1$, where $n$ is the principal quantum number. The possible values of $l$ correspond to the different subshells in an atom. For example, the s subshell has $l=0$, the p subshell has $l=1$, the d subshell has $l=2$, and so on.
The magnetic quantum number, $m_l$, determines the orientation of an atomic orbital in space. It can have values from $-l$ to $l$, inclusive. The possible values of $m_l$ correspond to the different degenerate orbitals in a subshell. For example, the s subshell has only one degenerate orbital, with $m_l=0$. The p subshell has three degenerate orbitals, with $m_l=-1$, $0$, and $1$. The d subshell has five degenerate orbitals, with $m_l=-2$, $-1$, $0$, $1$, and $2$.
The spin quantum number, $m_s$, determines the spin of an electron. It can have values of $+1/2$ and $-1/2$. The two possible values of $m_s$ correspond to the two possible spin states of an electron.
In conclusion, the azimuthal quantum number determines the shape of an atomic orbital, while the magnetic quantum number and spin quantum number determine the orientation and spin of an electron in an atomic orbital.