Metaphor - A figure of speech that describes a subject by asserting that it is, on some point of comparison, the same as another otherwise unrelated object.
Hyperbole - Exaggerating statements or claims that are not to be taken literally.
Personification - The attribution of a personal nature or human characteristics to something nonhuman, or the representation of an abstract quality in human form.
Alliteration - The occurrence of the same letter or sound at the beginning of adjacent or closely connected words.
The right answer is d. flatest and the proper spelling rule is to double the consonant when addix a suffix. The same happens in nouns/ adjectives like hot > hotter, jam > jamming.