The correct answer is No correction needed
Step-by-step explanation:
The section "If it were not so, there would be no one to tell of its harshness, beauty, and power" explains the qualities of the land described by grandmother. In this context, it is necessary, the elements listed are all nouns because the specific features are mentioned. Also, the qualities are preceded by the possessive noun "its" and therefore, this word should be followed by a noun. For example, in the sentence "I love his patience and intelligence", the possessive pronoun "his" is followed by the nouns patience and intelligence. Thus, the words "harshness, beauty, and power" are completely correct and do not need to be modified because all of these are nouns.
On the other hand, the option "harsh, nice and powerful" includes adjectives that are used before a noun, while the option "beautifully, powerfully and harsh" contains adverbs that are used to describe verbs.