Why does King Mark of Cornwall eventually kill his nephew, Tristam, after sending him to fetch his wife?
a. because Merlin told King Mark to sacrifice Tristam to maintain peace in his kingdom
b. because King Mark did not approve of Tristam befriending King Arthur
c. because King Mark does not want Tristam to take over his throne
d. because he suspects Tristam and Iseult to be in love with each other