Step-by-step Solution:

The correct spelling of the word is opportunity, which refers to a favorable set of circumstances or a chance to do something. Let us analyze the options: (a) opportunity - This is the correct spelling.\[\] (b) opoorrtunity - his is incorrect because of the extra "r."\[\] (c) ooportunity - This is incorrect because of the extra "o."\[\] (d) aportonity - This is incorrect due to significant misspelling and alteration of the word's structure.\[\] \[\] Correct Answer: (a)