Final answer:
Optically inactive structures do not possess chiral centers or asymmetric carbons. An example is cis-1,2-dibromocyclohexane, where the two bromine atoms are attached to the same side of the cyclohexane ring.
Step-by-step explanation:
Optically inactive structures are molecules or compounds that do not possess chiral centers or asymmetric carbons. One example of an optically inactive structure is cis-1,2-dibromocyclohexane. In this molecule, the two bromine atoms are attached to the same side of the cyclohexane ring, resulting in a plane of symmetry that allows for superimposition of the molecule onto its mirror image.