What is the total amount of heat required to vaporize 1.00 gram of h2o(g) at 100.0c and 1 atmosphere?
(1) 4.18 j(2) 334 j(3) 373 j(4) 2260 j

For this you will need the latent heat capacity for the vaporization of water. 

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.