Answer:
Definition of direct current. : an electric current flowing in one direction only and substantially constant in value
Explanation:
Direct current (DC) is the one directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current.
By knowing the distance between two objects we can not get enough ideas about the location of these respective objects. It can be easily understood from a simple example.
Let us consider two bodies A and B which are in a two dimensional plane. .Let the co-ordinates of body A is [2,2].
Let us consider two possible co-ordinate pairs [1,0] and [0,1]
Let the body B is at [1,0].
Hence the distance between A and B is
Let the body B is shifted to [0,1] now.
Now the distance between A and B will be
Here we observe that distance in each case is same .But in first case the body B was on +X- axis while in second case the body B was on +Y- axis.
Hence distance between points may be same in different planes, but only the distance can not get enough ideas about the location of the objects.It is the points in specific reference frames gives the ideas about the location of the objects. As position is relative ,hence for complete location of a object,the observer also plays a vital role here.
The answer is going to be A