Which of the following reactions is balanced?

A)

Sn2+ + 2Fe3+ → Sn4+ + 2Fe2+

B)

Sn2+ + 2Fe3+ → Sn4+ + Fe2+

C)

Sn2+ + Fe3+ → Sn4+ + Fe2+

D)

2Sn2+ + Fe3+ → 2Sn4+ + Fe2+