Which of the following type of memory is used to store the configuration used by the switch when it is up and running?

(A) ROM
(B) RAM
(C) NVRAM
(D) Flash

RAM is the correct answer. Switches (and routers) keep the currently used configuration in RAM.

RAM: Sometimes called DRAM, for dynamic random-access memory, RAM is used by the switch just as it is used by any other computer: for working storage. The running configuration file is stored here.