How did the death of Mary Queen of Scots contribute to a holy war between England and Spain?

i watched the show reign and they told me its on netflix at the end when she got her head cut off and francis died then mary died there was nobody left to lead and England wanted marys throne so they fought for it but spain was the same situation i believe

answer; /// the only one of the above that makes good sense is ( the poor,plz check luck

the answer is d. amendments.