Will mark as brainliest. this diagram would represent the enthalpy changes in which of the following? cold pack hot pack melting solid boiling liquid

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.