Add Like Terms, If Possible, and Write the Result in Descending

Add like terms, if possible, and write the result in descending powers of the variable.
--10m⁶ + 12m⁴ - 12m³ + 8m⁶ - 7m⁴

A) 5m¹³
B) -2m⁶ + 5m⁴ - 12m³
C) 65m
D) Cannot _{be simplified}