Answer: c
Explanation:
I can't tell the answer but here is how you get.
Pythagroean theorm states a^2+b^2=c^2.
Hypotnuse is c.
Create a triangle by connecting the two points with a straight edge. That line is c. The other two lines are from the point with y=1 to y=0, and connect that to the other point with y=0. The two lines created are a and b. Square the length of those lines, add them, and get the square root of that.