Final answer:
The corrected sentence fixes the plural and possessive errors, using the possessive form 'Great Wall's' and ensuring the proper use of commas for clarity. The sentence should be corrected to: “The Great Wall of China is one of the most striking feats of construction in history. Built over the course of several centuries, and consisting of many smaller fortifications, the Great Wall's original purpose was to prevent nomads from invading China.”
Step-by-step explanation:
The sentence should be corrected to: “The Great Wall of China is one of the most striking feats of construction in history. Built over the course of several centuries, and consisting of many smaller fortifications, the Great Wall's original purpose was to prevent nomads from invading China.”
Here, the possessive form “Great Wall's” is used to show that the original purpose belonged to the Great Wall, and the plural form “centuries” is correct as it refers to multiple centuries. Additionally, commas are added for clarity after 'history' and before 'and consisting' to separate the introductory phrase and to set off the non-restrictive clause.