Answer:
1.
To back up the scientist, when a person is more fit, their breathing will return to a normal rate faster than average, as B's rate returned faster than everyone else's, they are more fit.
Another reason the scientist could be right, is when a person is very athletic and fit, their resting heart beat is lower than an average person's heart rate. As person B has the lowest at 10, this would make them more fit.
2.
If the scientist counted wrong at all while measuring breath rates, the results could be wrong.
If each person did a different form of exercise, the results could also be wrong as different forms of exercise for each person would make the expirement inconclusive. (some exercises take more from the body than others).
Step-by-step explanation: