Directions: Select the option that fills in the blanks most suitably (in the same order).

There are several theories which try to ________ the functional ________ for the stripes found in Zebras, though none of them is fully ________.

See the answer option, theories can try to explain or predict and not forecast as given in option (2). All three words, aspect, cause and reason can suitably fill second blank to make good sense. Word grasped will make sentence grammatically incorrect. We cannot use term amusing, as there is no tone of humor in the sentence. Therefore, option (4) is correct answer.