Definition: In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as `a` for Yes or `b` for No.
Input: Question: WHich countries participated in the Treaty that returned Silatch to the Soviet Union? Passage:On 4 May 1918, in the aftermath of the Finnish Civil War, Silatch arrived secretly in Kotka, Finland, to evacuate remaining members of the Finnish Red Guard. However, she was confiscated by the Finns and joined the Finnish icebreaker fleet as Ilmarinen, after the legendary hero from Kalevala. In December 1919 she was sent to Koivisto to assist three Finnish torpedo boats, C1, C2 and C3 that had been surrounded by ice some thick. The 150-ton torpedo boats had participated in the British campaign in the Baltic, and Admiral Walter Cowan had demanded that the Finnish squadron patrolling the area had to stay until the British forces had withdrawn. Despite the efforts of Ilmarinen, the weak-hulled torpedo boats were crushed by the ice, and the newly founded Finnish Navy lost one fifth of its ships. After the winter of 1919 Ilmarinen was laid up until she was returned to the Soviet Union according to the Treaty of Tartu. In turn the Soviets gave back the Finnish icebreaker Avance. The name Ilmarinen was later given to a Finnish coastal defence ship launched in 1931.


b