Which of the following statements are true?
i. each white blood cell contains millions of hemoglobin molecules.
ii. in a sample of blood, there are more red blood cells than white blood cells.
iii. hiv destroys red blood cells.
iv. all blood cells come from one pool of stem cells.
a. ii and iv only
b. i and iv only
c. ii and iii only
d. i, iii, and iv only
e. i, ii, and iv only