I say the answer is B. (Reffering to a recent science article talking about "The hope of treating myocardial infarction with stem cells".)
A stem cell (CS), in particular embryonic, is a mother cell, called "pluripotent", capable of both self-renewal in the long run and to differentiate in any cell type (heart, bone, etc.). Their therapeutic interest is to regenerate damaged tissues or organs, a less burdensome alternative to organ transplantation.
We use CD34 + (adult CS) found in bone marrow because they persist throughout life and can act on various possible body tissues. these can create new blood vessels and regenerate myocardial tissue. Finally, they are the only ones able, at each of their division, to give at the same time a myocardial cell by differentiation and a new stem cell which ensures the durability of the graft.
