Final answer:
The observed structure for forms of a molecule or ion is an average of the resonance structures, referred to as a resonance hybrid. Therefore, the correct option is a) Hybrid.
Step-by-step explanation:
The correct answer is a) Hybrid.
When it is possible to write more than one equivalent resonance structure for a molecule or ion, the actual structure is the average of the resonance structures. This average structure is called a resonance hybrid. Resonance occurs when two or more Lewis structures with identical arrangements of atoms but different distributions of electrons can be written. The resonance hybrid represents the overall delocalization of electrons within the molecule or ion.