Generally, to make the plural of most words, we add an 's' at the end. We also do not add an apostrophe (the symbol ') to form plurals, rather we use it show possession. This rules out Option C); and Option D) is incorrect as it is not even a word. In this particular case, there are two equally valid answers - Options A) and B). Both 'syllabi' and 'syllabuses' are acceptable plural forms of the singular form 'syllabus'.