I believe the correct answer is the third option - “they became more fearful and also, in many cases, more suspicious of Muslims.”
Despite the fact that the Muslim-American community has played a crucial role in helping government officials detect and counteract roughly 2/5 of all Al-Qaeda based terrorist plans against the U.S, Islamophobia became very prevalent in the general American psyche post-9/11. I got that statistic & the attached graph from news.gallup.com, which offers more information on the subject if needed. Let me know if you have any questions.