39.Manhattan distance is measure along which of the following?  A. right angles  B. reflex angle  C. straight line  D. 180 degree

Step 1: Break Down the Problem

We need to determine the characteristic of Manhattan distance and identify among the options provided which aligns with its definition.

Step 2: Relevant Concepts

Manhattan distance, also known as "taxicab" or "city block" distance, is measured as the sum of the absolute differences of their Cartesian coordinates. It is calculated in a grid-based system, which means the movement is restricted to right angles.

Step 3: Analysis and Detail

In a grid-like path (like that in a city), to move from one point to another, you can only move horizontally or vertically. This means that:

$D_{Manhattan} = |x_1 - x_2| + |y_1 - y_2|$

Where $(x_1, y_1)$ and $(x_2, y_2)$ are the coordinates of the two points.

Step 4: Verify and Summarize

Since Manhattan distance only involves movements at right angles, option A is the correct choice.

Final Answer

A. right angles