What do these layers and their fossils suggest about Earth's history? ОА.
Lifeforms on Earth have been the same over time.
ОВ.
No lifeforms were present when these layers formed.
OC. Only one kind of lifeform lived where these layers formed.
OD
There have been changes in Earth's lifeforms over time.

This is the There have been changes in Earth's life forms over time.

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.