Final answer:
The correct answer is 3) no change.
The appropriate punctuation is to not replace any commas with semicolons in the example sentence provided. The use of semicolons is for connecting independent clauses, and in this case, the clause following 'important' is not independent.
Step-by-step explanation:
The student is asking about the proper use of punctuation marks, specifically the comma and semicolon, in the context of consumer marketing history. To answer question 1), you would need to replace the comma after 'marketing' with a semicolon to correctly connect two independent clauses that are related to each other, as in Example 1 - The roof of that car was covered in Astroturf; a strange sight!
For question 2), replacing the comma after 'important' with a semicolon is incorrect because the clause that follows is not an independent clause that could stand alone as a sentence. The correct answer is 3) no change, as the comma after 'important' appropriately separates the introductory clause from the main clause. The provided sentences are examples of correct punctuation usage that help delineate different statements and structural elements within a sentence.