I believe that the answer is most likely C.
Answer:
They acted as though they new all about the people from Iran. They were rude to them. They even had bumper stickers that said, "Iranians:" Go Home". Americans just don't understand how not all Iranian people are bad.
Explanation:
For example, if you sign up for a credit card, you may think the bold print is good, but the small print may reveal that the interest rates are not what they need to be. Secondly, it could put you into a lot of debt if you click the I agree button, but you didn't know that they can lower your credit score, or even totally damage it.
Present tense is the best choice to describe an ongoing action when another one occurs