The correct option is D Electric pole
Out of all the sub-stations involved in the power transmission from the power-plant, only the grid sub-station steps up the incoming voltage from 11 kV to 132 kV before transmitting it over to the main sub-station.
The reason for this is to avoid high power losses due to the low transmitting voltage. Transmitting the power at a high voltage reduces the risk of heavy currents too.
And, the electric pole that connects the household to the city sub-station also does not step up or step down the transmitting electric power.