A student was asked to answer the following question: A pot holding $1\,\text{L}$ of water initially at $20\,^\circ \text{C}$ is left unattended on a hot element. All of the water boils away. How much heat is transferred from the element to the water during the process?

The student's answer included all of the features below. Select all element are definitely incorrect, i.e. for which the grader will certainly deduct points.

A. A sketch of the physical system

B. A calculation: $Q = mc \Delta T$
C. A minor unit error in the calculation
D. A final answer (in kJ, not in J)