Concept:A shadow forms when an opaque object blocks light, creating a dark region behind it.
Explanation:An opaque object does not allow light to pass through it.
It blocks the light falling on it, producing a dark area on the opposite side.
This dark area is called a shadow.
A transparent object allows light to pass through, so it does not form a shadow.
A shadow is visible when it falls on a surface, such as a screen or the ground.
Thus, the true statements are: shadow is formed by an opaque object and it is formed on a screen.
Answer:D. II and III only