Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: A person in a dark room looking through a window can clearly see a person outside in the daylight. But a person outside cannot see the person inside. Why does this happen?
There is not enough light being reflected off the person in the room.
Light travels from the source to the observer. In this case, light from outside enters the room and allows the person inside to see outside, but light