The answer would be<em><u> option B. The Empire suffered from political and economic instability.</u></em>
Explanation:
First we should know that the Pax Romana is known as <em>a long period of hegemonial peace and stability (thus not without wars, expansion and revolts)</em> <em>experienced by the Roman Empire</em>. After that period however, the Roman Empire found itself in a big disaster because the consequences of that period left Rome in a political and economic instability.