Definition: 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.
Input: Question: Where does the body of water where Dr. Nelson G. Blalock established an agricultural operation originate? Passage:The community was named for the farm of Dr. Nelson G. Blalock, a Civil War veteran who had pioneered in the Walla Walla area. He established an agricultural operation of several thousand acres on the flat land here along the Columbia River. The area was first settled in 1879, and Blalock post office was established in 1881. The town was platted in 1881 by the Blalock Wheat Growing Company. The first two buildings, a railroad station and a warehouse, were built by A. J. McLellan, OR&N superintendent of the construction of bridges and buildings. By 1884, the community was shipping wheat and there were daily stagecoaches to Heppner; the population was 50. People and businesses listed in the Polk Directory at that time included two clergymen, a saloon, a wagonmaker, a ferryman, a hotel, a general store, a lawyer, and a dealer in lumber, coal, and feed. In 1904, the town handled about 750,000 bushels of wheat. By 1905, the town had two grain warehouses, a hotel, a general store, a livery and stage stable, a real estate office and an agricultural implement factory. In 1940, Blalock had a population of 19. The post office closed in 1959. In 1968, the community was inundated by the backwaters from the John Day Dam.


b