is when measurements are in the same area but not necessarily correct, where as is when at least one measurement is correct

it's c (engineer's do their work with mechanical stuff not on any living being)

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.