The correct answer is B. Euclidean distance.
The Euclidean distance is the most common way to measure the distance between two points in a plane. It is calculated using the Pythagorean theorem, which states that the square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides.
The formula for the Euclidean distance between two points $(x_1, y_1)$ and $(x_2, y_2)$ is:
$$d(x_1, y_1, x_2, y_2) = \sqrt{(x_1 – x_2)^2 + (y_1 – y_2)^2}$$
The Euclidean distance is a metric, which means that it satisfies the following properties:
- It is non-negative.
- It is symmetric.
- It satisfies the triangle inequality.
The non-negativity property means that the distance between two points is always non-negative. The symmetry property means that the distance between two points is the same regardless of the order in which the points are given. The triangle inequality means that the sum of the distances between any two points and a third point is always greater than or equal to the distance between the first two points.
The Euclidean distance is a useful measure of distance in many applications, such as finding the shortest path between two points on a map.