According to the Mayo Clinic, a female patient is considered to be anemic if her blood hematocrit value (the proportion of the blood made up of red blood cells) is lower than $35\%$.
A doctor takes a small sample of her patient's blood to check for anemia and measures the hematocrit value to be $38\%$. Which of the following statements is true?
I. 38% is the population parameter.
II. The blood drawn by the doctor is the sample for this study.
III. The doctor obtains a sample of blood from the patient in order to draw a conclusion about the population of the patient's blood.