Which punctuation change will correct this sentence The people are especially proud of their architecture they certainly should be.?

The correct punctuation change is to add a comma after "architecture".

Here's why:

* The sentence is a complex sentence: It has two independent clauses (complete thoughts) joined by a coordinating conjunction ("they").

* Commas are used to separate independent clauses: This helps make the sentence clearer and easier to read.

The corrected sentence is: The people are especially proud of their architecture, they certainly should be.