Hemoglobin, a substance in human blood, transports oxygen from the lungs to the rest of the body. With each oxygen mo...

SamA on June 7, 2020

Hello @alliehall21,

The difference between A and C brings up an important point. A key concept to understand here is relativity. With each additional molecule, it becomes more likely that hemoglobin picks up another molecule. However, we cannot say that a 4th molecule will probably be acquired. "More likely" is not the same as "probably," because "more likely" is relative to something else. It is true that hemoglobin will be more effective collecting the fourth molecule than the first. However, this could have been an increase from 10% to 35%, for example. We cannot conclude that a fourth molecule is probable.