They are using a form of imagery in this phrase. The train carts are not literally ice cubes bobbing up and down. It's used to help the reader imagen the scenario. Always refur to a "sentance/quote" as a 'phrase'. And use things like further more and moreover to get yourself good grades. Good luck
I think the answer is either A. Why does Harry seem sad at the end of the passage. or D. Where will jack and Harry find work after the professor leaves?
A joint resolution is when the ideas come together . For example in this plot the character learns the facts , which means the ideas become connected ( joint resolution )