The correct option is D cacti
Generally when a word ends with 's' already, we do not add an 's' to the word to make it plural, nor do we add an apostrophe (the symbol ') as that is used to show possession, not plural. This rules out Options A) and C); and Option B) is incorrect as it is not even a word. This leaves us with the correct answer - Option D). The word 'cacti' is the specific plural for the singular form 'cactus' , making this an exceptional case.