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: How old was General Sir William Robertson when he selected Hugh Elles to liasise with troops? Passage:In August 1915, after recovering from his injuries, Elles was one of three officers specially selected by General Sir William Robertson, soon to be Chief of the Imperial General Staff (CIGS), the professional head of the British Army, to liaise with troops at the front and pass the information directly to the British General Headquarters (GHQ). In January 1916, as a General Staff Officer (GSO), Elles was sent by General Sir Douglas Haig, the Commander-in-Chief (C-in-C) of the BEF on the Western Front, to investigate the first tanks or "caterpillars" being built in England. He attended the first trials of "Mother" and reported back to Haig on its success. During the summer of 1916, he was tasked to report back from the Somme, where the tanks were first used. Elles was appointed to head the Heavy Branch (the first tank units) of the Machine Gun Corps in France on 29 September 1916, with the temporary rank of colonel. His responsibilities included its advanced training and tactical employment. He also commanded the large central depot and workshops established near Bermicourt.


b