Which of the following chemical equations is balanced correctly?

a
4CaO + 10C -> 4CaC2 + 2CO2

b
SO3 + H2O -> H2SO3

c
2Al + Fe2O3 -> Al2O3 + Fe

d
B2O3 + 2C -> B4C + CO2

c

2Al + Fe2O3 -> Al2O3 + Fe