I think its going to be the 2nd option class's. even the you usually put an apostrophe after the s when the noun is plural, I believe class's is a collective noun in this place which take a singular approach with apostrophes
A thesis statement is generally the first few sentences of your writing to help get your readers interested in what they'll be reading. So, if your thesis is unclear, they'll be confused about what's going on before anything even happens.
For example, the dog ran over the fence, tripped and fell.
The story Chasing Two Rabbits is an example of Zen parable.
