In which of the following examples has a chemical reaction occurred? Group of answer choices

After putting liquid batter into a hot pan, the batter solidifies and begins to turn brown.

After turning on a blender filled with fruits, the fruit is chopped up and mixed together.

After taking a tray filled with ice cubes out of the freezer, the cubes begin to melt.

After adding a spoonful of sugar to a mug of hot coffee, the sugar dissolves completely.