Answer:
2
Step-by-step explanation:
First, you do the subtraction 120-21.4 which is 98.7. So since you know its x^7, the number isn't going to be big. By guessing and checking, we start with 2. 2^7 is 128. We know that 1^7 would just be 1, so the closest whole number would be two.
The answer is 3 for this question.
The answer is between B and C but... I'm kinda leaning more towards B but, you choose which one you think is right.
Hope I helped you. :)