A. A uniform of McKay.B. A footnote about McKay.C. A bo……

Eddie McKay, a once forgotten pilot, is a subject of great interest to a group of history students in Canada.
It all started when Graham Broad, a professor at the University of Western Ontario, found McKay’s name in a footnote in a book about university history. Mckay, was included in a list of university alumni who had served during the First World War, but his name was unfamiliar to Broad, a specialist in military history. Out of curiosity, Broad spent hours at the local archives in a fruitless search for information on McKay. Tired and discouraged, he finally gave up. On his way out, Broad’s glance happened to fall on an exhibiting case showing some old newspapers. His eye was drawn to an old picture of a young man in a rugby uniform. As he read the words beside the picture, he experienced a thrilling realization. "After looking for him all day, there he was, staring up at me out of the exhibiting case," said Broad. Excited by the find, Broad asked his students to continue his search. They combed old newspapers and other materials for clues. Gradually, a picture came into view.
Captain Alfred Edwin McKay joined the British Royal Flying Corps in 1916. He downed ten enemy planes, outlived his entire squadron as a WW1 flyer, spent some time as a flying instructor in England, then returned to the front, where he was eventually shot down over Belgium and killed in December 1917. But there’s more to his story. "For a brief time in 1916 he was probably the most famous pilot in the world," says Broad. "He was credited with downing Oswald Boelcke, the most famous German pilot at the time." Yet, in a letter home, McKay refused to take credit, saying that Boelcke had actually crashed into another German plane.
McKay’s war records were destroyed during World War Two air bombing on London-an explanation for why he was all but forgotten.
But now, thanks to the efforts of Broad and his students, a marker in McKay’s memory was placed on the university grounds in November 2007. "I found my eyes filling with tears as I read the word ’deceased’ next to his name," said Corey Everrett, a student who found a picture of Mckay in his uniform. "This was such a simple example of the fact that he had been a student just like us, but instead of finishing his time at Western, he chose to fight and die for his country.\
What made Professor Broad continue his search for more information on McKay

A. A uniform of McKay.
B. A footnote about McKay.
C. A book on McKay.
D. A picture of McKay.