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.

Question: Was Ejei Khan from Chahar Borjigin? Passage:When the Northern Yuan Chahar Borjigin Mongol Khan Ejei Khan surrendered to the Qing, he was given the title of Prince of the first rank (Qin Wang, ), a title he held until his death in 1661, and inherited by his younger brother Abunai (). Abunai openly showed his discontent toward the Manchu and he was put under house arrest in Shenyang by the Kangxi Emperor in 1669 and his imperial title / rank was given to his son Borni () in September of that same year. Borni () was careful to not show any sign of disrespecting the Qing Dynasty, but finally in 1675, he suddenly rebelled along with his younger brother Lubuzung (), capitalizing on the Revolt of the Three Feudatories. However, they had made a serious miscalculation in wrongfully believing that other Mongols would join them, when in reality only three thousand Chahar (Mongols) joined the rebellion. It only took a single decisive battle on April 20, 1675 to defeat Abunai () and his followers, who were all killed subsequently in their retreat. The Qing Dynasty's punishment of the rebellion was very harsh: all royal males of Chahar (Mongols) were executed, including infants born to Qing / Manchu princesses, and all royal females of Chahar (Mongols) were sold to slavery except these Qing / Manchu princesses.
Links: a. Shenyang b. Kangxi Emperor c. Ejei Khan d. Borjigin
c