Which Is an Example of a Physical Change

Which is an example of a physical change?

A) The milk in the box left on the table becomes sour after a few days.
B) The bit of scrap metal dissolves when placed in the container of acid.
C) The gas is cooled until it finally becomes a liquid.
D) A piece of paper burns in air with a smoky flame.
E) Bubbles are seen on the egg shell after some vinegar is poured on it.