Detailed Instructions: In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it, i.e., the proper nouns in the passage. Your job is to determine whether information from more than one term is needed to answer the question. Indicate your choice as 'a' for Yes or 'b' for No.
Problem:Question: Where was the battle fought that the Sassanid were defeated in? Passage:After their defeat at the Battle of Walaja, the Sassanid survivors of the battle who consisted mostly of Christian Arabs fled from the battlefield, crossed the River Khaseef (a tributary of the Euphrates) and moved between it and the Euphrates. Their flight ended at Ullais, about 10 miles from the location of the Battle of Walaja. The Muslims were aware of the presence of hostile Arabs at Ullais but, as they were less numerous and were survivors of Walaja, they never considered them a military threat until they started to regroup and the Muslim commander Khalid ibn Walid was informed about the arrival of more Arab hordes, mainly from the Christian Arab tribe of Bani Bakr. More reinforcements were raised from the Christian Arab tribes in the region between Al-Hirah and Ullais. The Rashidun Caliphate army under Khalid crossed the river Khaseef and approached Ullais frontally. Emperor Ardsheer meanwhile sent orders to Bahman Jaduya to proceed to Ullais and take command of Arab contingents there and stop the Muslims advance at Ullais. Bahman sent his senior general Jaban with the imperial army to Ullais with orders to avoid battle until Bahman Jaduya himself arrived. As Jaban set off with the army, Bahman Jaduya returned to Ctesiphon to discuss certain matters with the Emperor. He arrived at Ctesiphon to find Emperor Ardsheer very ill and remained in attendance on him. By now the Persians and Arabs had realised that the Muslims' objective was Al-Hirah. They decided to fight and defeat the Muslims army. The Christian Arab contingents were under the command of a tribal chief called Abdul-Aswad, who had lost his two sons in the Battle of Walaja against the Muslims and wanted revenge.

Solution:
b