Stem cells because they are compatible of dividing and renewing themselves after long periods
Answer:
Ar
Explanation:
Argon isn't with the metals on the periodic table
Zit sure has to be B. Pollution
None, Electrons are not in the nucleus
<em>They</em><em> </em><em>are</em><em> </em><em>pres</em><em>ent</em><em> </em><em>in</em><em> </em><em>orbi</em><em>ts</em><em> </em><em>or</em><em> </em><em>ene</em><em>rgy</em><em> </em><em>shells</em><em>.</em><em> </em>