Which of the following is laboratory preparation of dihydrogen?
A. `3Fe + 4H_(2)O(steam) rarr Fe_(3) O_(4) + 4H_(2)`
B. `2Na + 2H_(2)O rarr Ca(OH)_(2) + 2H_(2)`
C. `CaH_(2) + 2H_(2)O rarr Ca (OH)_(2) + 2H_(2)`
D. `Zn + H_(2)SO_(4)(dil.) rarr ZnSO_(4) + H_(2)`