Context: The passage below describes an experiment. Read the passage and think about the variables that are described.

Lucy's brother thought that crushed ice would keep his soda cooler than whole ice cubes.
To test this idea, Lucy divided a large bottle of soda equally among six glasses. Lucy added five whole ice cubes to each of the first three glasses while her brother crushed five ice cubes into small pieces before adding them to each of the other three glasses. Ten minutes after all the ice had been added to the glasses, Lucy used a thermometer to measure the temperature of the soda in each glass.
Hint: An independent variable is a variable whose effect you are investigating. A dependent variable is a variable that you measure.
Figure: glasses of soda with ice.
Which of the following was an independent variable in this experiment?
A. the temperature of the soda
B. the size of the ice pieces
From the given choices, select the correct answer and reply with the letter of the chosen option.

B