Concept:Light travels in straight lines, so an opaque object stops light from reaching the space behind it.
Explanation:An opaque object does not allow light to pass through it.
When light rays hit this object, they are completely blocked.
Since light cannot bend around the object, the region directly behind it remains dark.
This dark area formed on the surface beyond the object is called a shadow.
An echo is caused by reflected sound waves, not light.
A penumbra and an umbra are specific parts of a shadow made by an extended light source, but they are not the general name for the dark region formed.
Answer:B. Shadow