Given the task definition and input, reply with output. 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.

Question: Was the engineer who designed the framed tube structures used in One World Trade Center older than 40 when he designed them? Passage:The towers were designed as framed tube structures, giving tenants open floor plans, unobstructed by columns or walls. The framed tube design was introduced by Bangladeshi-American structural engineer Fazlur Rahman Khan in the 1960s. The design was accomplished by using many closely spaced perimeter columns, providing much of the structure's strength, with the gravity load shared with the core columns. The elevator system, which made use of sky lobbies and a system of express and local elevators, allowed substantial floor space to be used for office purposes by making the structural core smaller. The design and construction of the towers involved many other innovative techniques, such as wind tunnel experiments and the slurry wall for digging the foundation. Yamasaki also incorporated elements of Islamic architecture in the building's design, having previously designed Saudi Arabia's Dhahran International Airport with the Saudi Binladin Group.
b