The electrons in an atom's outermost energy level are called: Electron dots. Quantum electrons. Valence electrons. Noble-gas electrons.

The valence electrons are located in an atom's outermost energy level

In an atom, there are levels of energy in the shell and subshell  

This energy level is expressed in the form of electron configurations.  

Electrons fill the orbitals based on the Aufbau principle, namely the filling of electrons starts from the lowest energy level

Usually used in describing Lewis structures, placed around the element

Each orbital in an atom consists of 4 quantum numbers  : n, l, ml, ms

Each electron has a different quantum number and this conforms to Pauli's rule: no electrons have the same 4 quantum numbers

Valence electrons are electrons used in a chemical bond , and  in an atom's outermost energy level

Noble gas has a stable electron configuration of 8 valence electrons which guides the formation of chemical bonds called the octet rule

the answer is option a.