Pashu aur pakshiyon ki sahyata aur dekhbal par lekh likhe

Late at night some traffic signals change patterns and become ?

Luminous objects such as flashlights emit light that we can see. how do we see an object that isn’t luminous? a. the object emits light that reaches our eyes. b. light reflects off the object and reaches our eyes. c. light passes through the object uninterrupted. d. light is fully absorbed by the object. e. we can’t see an object that isn’t luminous.

How do you work out 21.3-8= show your working. plz