Given the following reactants, finish and balance the reaction:
Ca(s) + HCl(aq) -->
A. Ca + 2 HCl --> CaCl2 + H2
B. 2 Ca + 2 HCl --> 2 CaCl + H2
C. Ca + HCl --> CaCl + H
D. Ca + 2 HCl --> CaCl2 + 2H