Concept:The correct spelling of the word meaning a formal assurance or promise is 'Guarantee'.Explanation:The word 'Guarantee' is spelled with double 'e' at the end. The other options contain common spelling errors.Option B 'Guarantiy' wrongly uses 'y' instead of 'ee'.Option C 'Guarentee' incorrectly places 'e' before the final 'ee', changing the vowel order.Option D 'Guarantie' ends with 'ie' instead of 'ee'.Only option A matches the standard English spelling.Answer:Option A. Guarantee