Red blood cells in mammals ____.

Red blood cells in mammals ____.
 
  a. have a large nucleus when they enter circulation
  b. do not have a nucleus when they enter circulation
  c. are the only cells to lack hemoglobin
  d. develop in the yellow marrow
  e. function as part of the immune system

Question 2

Beginning with the heart, which is the correct order of blood flow, as represented by steps 1-5 in the flow chart below?
 
  a. capillaries, venules, veins, arteries, arterioles
  b. arterioles, arteries, venules, veins, capillaries
  c. arteries, arterioles, capillaries, venules, veins
  d. veins, venules, capillaries, arterioles, arteries
  e. arteries, veins, arterioles, capillaries, venules