Final answer:
Option 1 is the best choice as it combines the two sentences with a comma and 'which', making the obelisk's shape clear without creating a run-on sentence.
Step-by-step explanation:
The most effective way to combine the sentences "Some members of the Sons of Liberty constructed a paper obelisk." and "An obelisk is the same shape as the Washington Monument." is by using Option 1: constructed a paper obelisk, which is the same shape as the Washington Monument.
This option appropriately combines the two sentences with the use of a comma and the relative pronoun 'which', providing additional information without creating a run-on sentence.
The most effective way to combine sentences 1 and 2 is option 1: "... constructed a paper obelisk, which is the same shape..." This option uses a relative pronoun ("which") to introduce additional information about the paper obelisk, creating a clear and grammatically correct connection between the two sentences.
The use of a comma before "which" helps to maintain the flow of the sentence. Options 2 and 3 have issues with punctuation and clarity, and option 4 introduces a semicolon, which is not the most suitable choice for connecting these two related ideas.