Objects which emit light of their own are called:
A. Non-luminous objects
B. Transparent objects
C. Translucent objects
D. Luminous objects

Hint: First we need to know each of the definitions given in the options and after that comparing each of them with each other we can find our solution. Not every object has their own light, some also does not emit light, some objects allow the light to pass while some do not. Now using this concept we can solve the problem.

Complete answer:
We know that light is a combination of both electric and magnetic which can pass through two types of objects one is transparent and another one is translucent. Now if we see option (B) and (C) we can say that the objects which allow the light to pass through them completely with any kind of obstruction are called transparent objects and the object which allow the light to pass through its partially is called translucent objects respectively.

Option (A) is non luminous objects which means there are the objects which do not emit light on their own. In other words we can say that the object which does not have its own light and it is just opposite to option (D) that of luminous objects which give out light of their own.Hence from the above discussion we can say that luminous objects are the objects which emit light of their own.

Therefore the correct option is D.

Note: Remember there are so many luminous and non-luminous objects present. Some of the examples of luminous objects are the sun, flams in a lamp, tube light, electric bulbs and many more. Now some of the examples of non-luminous objects are the earth, moon, a piece of light, cola etc.