Given the task definition and input, reply with output. In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.

Question: When did the event where  Frank Alberry won a Distinguished Conduct Medal end? Passage:Frank Alberry, DCM (29 September 1892 – 23 January 1968) was an Australian soldier and airman who had a varied military career. Born in Hobart, he served in the Welch Regiment of the British Army before the First World War, but deserted. He joined up again in the early days of the First World War, and went on to serve with the 8th Battalion of the Australian Imperial Force. After service at Gallipoli, he joined the British Expeditionary Force in France. He won a Distinguished Conduct Medal at the Battle of Pozières, but lost a lower leg in the process. Alberry took the extraordinary step of personally petitioning King George V for permission to transfer to the Flying Corps, and subsequently became a flying ace credited with seven aerial victories. Alberry returned to service during the Second World War as a recruiter.
 Links: a. Distinguished Conduct Medal b. Battle of Pozières c. 8th Battalion (Australia) d. World War II

b