According to the wave-mechanical model of the atom, electrons in an atom
(1) travel in defined circles
(2) are most likely found in an excited state
(3) have a positive charge
(4) are located in orbitals outside the nucleus

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.