Here's why:

* Input vs. Output: An input device takes information from the user or the environment and sends it to a computer. An output device takes information from the computer and presents it to the user.

* Light Bulb Function: A light bulb doesn't receive information. Instead, it receives electrical energy as input and converts it into light, which is then output to the user.

Therefore, the light bulb acts as a visual output device, converting electrical energy into a form that humans can perceive.