C. is the answer. You can't use plastic because it does not conduct electricity and string does not conduct electricity either so the circuit will end before it get to the bulb.
The siren will seem to get louder as the ambulence approches, and it will seem to get quieter as the ambulence drives away.
The first law of thermodynamics can be written as

where

is the variation of internal energy of the system

is the amount of heat absorbed by the system

is the work done by the system on the surrounding.
Using this form, the sign convention for Q and W becomes:
Q > 0 --> heat absorbed by the system (because it increases the internal energy)
Q < 0 --> heat released by the system (because it decreases the internal energy)
W > 0 --> work done by the system (for instance, an expansion: when the system expands, it does work on the surrounding, and so the internal energy decreases, this is why there is a negative sign in the formula Q-W)
W < 0 --> work done by the surrounding on the system (for instance, a compression: when the system is compressed, the surrounding is doing work on the system, and so the internal energy of the system increases)
Radiation - it travels in all directions so when you place your hands above a fire radiation hits your hand and reveals to ur cells where they transfer that hear into electrical signals, making you feel heated