A) It is a noun.
In this case, the type of affix is called a suffix, and that suffix is '-ism'. It is called a suffix because it is added to the end of the word 'patriot', forming the noun 'patriotism'. If an affix is added to the beginning of a word, it is called a prefix. For example, adding the prefix 'dis-' to the word 'like' forms the word 'dislike' :)