I bet no one can solve this :)
![I bet no one can solve this class=](https://us-static.z-dn.net/files/d90/c379dd732d2240ee94b6339974d5be0e.png)
Answer:
it's D
Explanation:
The current can run through R because it is practically a closed circuit by itself so the lamp would be lit but, with S and T the current can not flow and light the lamps because the switch is open.