The answer is C. How we know:
The origional expression would equate to -0.3
The reason A is incorrect is that you can not change the order of subtraction. This answer equates to 0.3.
The reason B is incorrect is that adding is not the same as subtracting. This answer equates to 4.7.
The reason D is incorrect is that subtracting a negative is the same as adding. This would equate to 4.7
The reason C is correct is that adding negative is the same as subtracting. This would equate to -0.3.