the answer is c.
you have to multiply by -3 on both sides to get c on its own.
therefore, c is greater than or equal to -9.
in a, c is less than or equal to 9 so thats not the answer.
In b, c is greater than or equal to 9 but it has to be -9.
in d, c is less than or equal to -9.
the answer is c