In what ways does the magna carta promote the idea that even the king must be subject to the rule of law? what responsibilities does the king have?

On June 15, 1215, a disgruntled group of landed barons achieved a great if very short-lived victory over the reigning monarch of the time, King John.  That victory was the king’s consent to a document presented for his stamp that limited the monarch’s authorities vis-à-vis his subjects.  That document, the Magna Carta, was a detailed list of demands and principles that were intended to protect these elites from the tyranny of a king with unchecked powers.   This limitation on the taxation of the king’s subjects, and its prohibition on the enforced requisition of those subjects’ crops and other properties, remained a pillar of democratic thought for centuries to come, and was reissued several times over the ensuing years until it finally stuck.  Its influence on the British subjects residing in the Crown’s North American colonies who were contemplating the text of what would become the Constitution of the United States was considerable.  Those rebellious colonies were heavily influenced by the intellectual developments characteristic of the Age of Enlightenment, but central to those developments remained the principles established in the Magna Carta.  That this nation’s founders were similarly influenced by the 1215 document is evident in Alexander Hamilton’s essay defending the draft constitution and advocating for its ratification.  In that essay, designated Federalist Paper #84, Hamilton wrote the following:    “It has been several times truly remarked that bills of rights are, in their origin, stipulations between kings and their subjects, abridgements of prerogative in favor of privilege, reservations of rights not surrendered to the prince. Such was Magna Charta, obtained by the barons, sword in hand, from King John. Such were the subsequent confirmations of that charter by succeeding princes. Such was the Petition of Right assented to by Charles I., in the beginning of his reign. Such, also, was the Declaration of Right presented by the Lords and Commons to the Prince of Orange in 1688, and afterwards thrown into the form of an act of parliament called the Bill of Rights.”   In that passage, Hamilton recognizes the enduring influence of the Magna Carta, and of the document’s role in the evolution of political thought through the ensuing centuries.  The concept of limitations on the power of a ruler had sufficient appeal that it survived many monarchs’ efforts at resisting the relinquishment of authority the document stipulated.  The American Bill of Rights was a direct outgrowth of the evolution of political thought that didn’t begin with the Magna Carta, but for which the document represented perhaps its most important manifestation to date.

because their parents smoke while in labor

i would say b. or c.