The answer to your question would be that the sentence that joins the two sentences correctly by adding a subordinate clause is the following one: We collected shells because we wanted to use them to make a necklace. That is, the correct option would be D.
In this case, the subordinate clause introduced by the subordinating conjunction "because" introduces the reason why they collected the shells.
The fallacy that can be identified and that can be discredited is the idea that African American people are inferior based on perceptions from an earlier time.
