When I was in grade school, we'd run the mile for Presidential Fitness Testing once or twice a year. I always ran the entire way, very slowly, and ended with the taste of blood and iron in my mouth. Is this:

(a) totally normal,
(b) a sign that I was unusually out-of-shape for a fifth-grader,
(c) a sign that I was unusually stubborn for a fifth-grader,
or
(d) a sign that I had undiagnosed asthma?