The correct option is C gracious
Let’s examine the sentence: “God is _______.” The sentence is trying to state a quality attributed to God. So, the blank requires a word that defined a quality attributed to God. Option A or ‘graceful’ means ‘elegant’ and it cannot be used here as it can define a worldly entity and not God. Option C or ‘grateful’ means ‘thankful’ and so cannot be used here. Option D or ‘greatful’ is wrong as there is no such word in English and so cannot be used here. Option B or ‘gracious’ means ‘benevolent’ and so is the correct word to be used here. Hence, Option B is the correct answer.