What Does It Mean to Say That Haemoglobin Is Fully

Multiple Choice

What does it mean to say that haemoglobin is fully saturated

A) There is an oxygen molecule attached to each of the four heme groups.
B) Oxygen is attached to both the heme and the globin portions of the molecule.
C) Red blood cells contain as many haemoglobin molecules as possible.
D) Haemoglobin is carrying both oxygen and carbon dioxide simultaneously.