Answer:
B
Explanation:
In A, it says that 9s +7c can be lower or equal to 160. This is wrong.
In C, it says that 9s +7c can only be higher than 160, when the question says at least, which means it can also be equal to 160, making it wrong.
In D, it says that 9s +7c can be lower or equal to 20. This is wrong.
Through elimination, only B can be right.