In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: What country was Medina part of in 844? Passage:Hasan was born in Medina around 844. Hasan's father was a descendant of Husayn ibn Ali, the grandson of Muhammad and third Shi'a Imam, via his eldest son Zayn al-Abidin, while his mother was an unnamed Khurasani slave. When Hasan ibn Zayd, a descendant of Husayn's brother Hasan, established his rule over Tabaristan in the 860s, Hasan joined him there. However, he eventually fell out with Hasan ibn Zayd's brother and successor, Muhammad ibn Zayd, who distrusted him. Hasan left Tabaristan and tried to set up a realm of his own in the provinces further east. To this end, he allied himself with the ruler of Khurasan, Muhammad ibn Abdallah al-Khujistani, who was an enemy of Muhammad ibn Zayd. Soon, however, al-Khujistani too came to distrust him and had him imprisoned and scourged, as a result of which he lost his hearing and received the sobriquet al-Utrush ("the Deaf"), by which he is known.
Links: a. Muhammad b. Medina c. Hasan ibn Ali d. Hasan ibn Zayd
A:
b