I would say B. because the equations are always being divided by 7.
It could not be A because nothing is being multiplied
It could be B because everything is being divided by 7. So the variable would be 1, 2, 3, 4, because they are changing. 7 would be the dependent, if I’m not mistaken.
It could not be C because nothing is being added
It could not be D because, even though they are being divided, they are not being divided by a variable.
I’m sorry if I didn’t explain myself more. But, basically, the answer is B