Which of the following is a good electrical conductor ? a) wood b) plastic c) rubber d) copper

Hey there! :D

Most good electrical conductors are metal. Actually, rubber is used around wires as an insulator to help the current stay in a direct flow. Wood and plastic don't handle current very well, as it will most likely burn the wood and melt the plastic. 

"D" Copper is the best answer. 

I hope this helps!
~kaikers