Explanation
The odd one out is option B: Water : Tap.
All the other pairs in the options are related to each other in a specific way:
• A: Oil is used to fuel a lamp, i.e., oil is used as a source of energy to light up the lamp.
• C: Oxygen is essential for life, i.e., life needs oxygen to exist.
• D: Power is used to operate a machine, i.e., power is used as a source of energy to make a machine work.
However, in option B, water and tap do not have a direct cause-and-effect relationship. While water can come out of a tap, it can also come from other sources such as a well or a bottle. Therefore, B is the odd one out.