A 60W lamp is used for 5h each day, while a 75W lamp is used for 4h each day. Over a 30-day month, which statement about their energy consumption is correct?
(a) The 75W lamp consumes more energy than the 60W lamp.
(b) The comparison cannot be made without knowing the mains voltage.
(c) Both lamps consume the same amount of energy over the month.
(d) The 60W lamp consumes more energy than the 75W lamp.