What is the rule for the reflection?

The figure is being reflected over the x axis (horizontal axis). Any y coordinate that is negative becomes positive, and vice versa. The x coordinate stays the same. 

If we have some point (x,y) as the original point, then it would turn into (x,-y). Note how the y coordinate has a negative on it now. 

So we can say  which is what choice C is saying. 

Choice C is the answer

Choice D is NOT the answer because the words "y axis" under the 'r' should be "x axis" instead.

M< 5 = 80 , < 2 = 80, < 6= 100, < 3= 100, < 7= 80, < 4= 80, < 8= 100