Answer:
B. The volume of the liquid should be measured before it is heated.
Step-by-step explanation:
A student made serious mistake that he did not measure the volume of the liquid before heating.
The scientific experimentation along with care and attention need a proper protocol which a scientist needs to follow to get the results.
The initial hypothesis of the student shows that he wants to know the change in volume, so it is inevitable to calculate the initial volume to know the difference after the completion of experiment.
All other options seem less appropriate than Option B, therefore B is the right answer.
I hope it help!