A- My maternal grandmother is sixty-six.
B is incorrect as thunderstorms are one word that does not require a hyphen.
C is incorrect as herself is also a singular word. As for D, nine and days have no correlation other than it's used in the sentence. If anything, the hyphen would need to be placed between the twenty and the nine.
Hope this helps!
In order to persuade someone, the idea presented should be convincing through facts and arguments. The author of the passage claims that nothing is impossible by showing different scenarios in which the outcome seemed impossible at the time but was achieved anyways. People were able to climb Mount Everest, create a machine that help humans fly and even walk on the moon.
It means to have the quality of something.
I believe the answer would be D
