Given the task definition and input, reply with output. Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.

Context : Margareta Gyllenstierna af Fogelvik (1689 - died 26 January 1740), was a politically active Swedish countess, married to Arvid Horn, the President of the Privy Council Chancellery (1710--1719 and 1720--1738) and one of the leading figures of the Swedish Age of Liberty.
Answer : Arvid Horn
What is Margareta Gyllenstierna's spouse's name?