Riddle

Secured in place, I work undercover, and with a flick of your finger my purpose you'll discover. What am I?

Choose an answer

A.A switch
B.A doorbell
C.A remote control
D.Light bulb
Hint: It's a 2-word phrase with 9 letters, starting with "L".

Answer

Light bulb

Why this is the answer

A light bulb is fixed in its socket, hidden inside a fixture, and reveals its purpose the moment you flick the switch.

This riddle is filed under "What Am I?" Riddles and rated Medium.