Instructions: In this task, you're given a question, along with three passages, 1, 2, and 3. Your job is to determine which passage can be used to answer the question by searching for further information using terms from the passage. Indicate your choice as 1, 2, or 3.
Input: Question: What is the age difference between Harben's father and grandfather? Passage 1: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.
 Passage 2:He was the son of Henry Andrade Harben and the grandson of Sir Henry Harben who founded Prudential Assurance, Harben was educated at Eton College and Magdalen College, Oxford, before qualifying as a barrister. He married Agnes Helen Bostock. He stood unsuccessfully for the Conservative Party in Eye at the 1900 general election, but by 1902 had switched his affiliation to the Liberal Party. He stood for the Liberal Party in Worcester at the 1906 general election. Although he lost the election, he petitioned the election court on the grounds that supporters of the winner, George Henry Williamson, had engaged in widespread bribery. He won the case, but the seat was left vacant until a by-election in 1908, and the local Liberal Party adopted a new candidate. Harben next stood in Portsmouth at the December 1910 general election, but came bottom of the poll.
 Passage 3:Beagle is a crater lying within the Margaritifer Sinus quadrangle (MC-19) portion of the planet Mars, the crater is one of multiple topographical depressions within the Meridiani Planum extraterrestrial plain, which was explored by the Opportunity rover. It was located by the rover in images taken on sol 855 (June 20, 2006), 310 metres (1,107 ft) away. It is on the edge of the much larger ejecta blanket surrounding the crater Victoria, named the Victoria Annulus. This impact crater was named in honor of HMS Beagle of the Royal Navy, ordered in February 1817, which carried Charles Darwin on his voyage round the world.

Output:
2