-- Water cannot be boled.
-- There is no such thing as a coffe aker.
-- There is no such thing as an immension-type heating element.
Be that as it may, and it very likely still is, as it were . . .
-- The latent heat of vaporization of water at 100°C is about 2250 kilo-joules per kg.
-- To evaporate half of the kg of water in the coffee maker requires 1125 kJ of heat energy.
-- To supply that amount of heat energy over a period of 10 minutes (600 seconds), it must be supplied at a rate of
(1,125,000 Joules / 600 seconds) = 1,875 joules/second.
-- That's 1,875 watts, or 1.875 kilowatts.
-- Choice-a is the choice when the solution is rounded.
