Q1: The ________ ensures that only one IC is active at a time to avoid a bus conflict caused by two ICs writing different data to the same bus.

ANS:C - address decoder

Control bus just used to pass the control to the processor or to the devices connected (i.e.) in read operation control is given to devices to write on the address, whereas on the write operation the processor is given control to write on the memory. Thus is the work of control bus,

But whereas address decoder only correctly decodes the address and identifies which is needed to be operated and sends the signal to the control bus.