Having solid, outstanding, and excellent education is very important. However, having this without actual practice and appropriate it becomes useful. So, if you are knowledgeable and astute person but you fail to display by being humble, gentle, and simple this your solid knowledge couldn't help you to establish the foundation of your knowledge and expertise.
Since a participle takes the form: verb + -ing, the only word in this sentence which has such a form is B, 'challenging'. 'Puzzle' is a noun, 'crossword' is an adjective, 'created' is a verb.
