Explanation:
I think you are missing the square root signs or so in the answer options.
the distance between 2 points is calculated by using Pythagoras for right-angled triangles.
c² = a² + b²
c is the Hypotenuse of the triangle and the distance between the points, which are the end points of the Hypotenuse.
a and b are the legs and enclose the 90 degree angle. they are the differences of the x and y coordinates between the 2 points.
so,
distance² = (1 - -7)² + (6 - 3)² = 8² + 3² = 64+9 = 73
=>
distance = sqrt(73)