Concept:In a number series, one term may not follow the common rule and is called the odd term.Explanation:The pattern is that each term should be the previous term multiplied by 7.Check the second term: 2289×7=16023, not 16221.Using 16023, the remaining terms match perfectly:16023×7=112161112161×7=785127785127×7=5495889So 16221 breaks the pattern.Answer:The odd term is 16221, i.e. option B.