Concept:Spelling errors often involve doubled letters; knowing the correct form of common words is essential for exams.
Explanation:The misspelled word is 'Garulous' (option D). Its correct spelling is 'Garrulous' (with double 'r').
Garrulous is an adjective meaning excessively talkative about trivial matters.
Example: The garrulous man kept talking for hours without a pause.
All other options are spelled correctly: 'Garrulous' (option A) is the correct spelling of that word, 'grateful' means thankful, and 'guarantee' means a promise or assurance.
Only option D has a missing 'r' and is therefore the incorrect spelling.
Answer:Option D: Garulous (correct spelling – Garrulous)