Mr. Henderson always wears neat clothes and his hair is always perfectly combed. He looks very serious because he rarely smiles and always speaks in a calm, formal tone. People think he is strict, but he is actually very fair and patient with his students.
Why do people think Mr. Henderson looks serious?
A) Because he wears neat clothes.
B) Because his hair is perfectly combed.
C) Because he rarely smiles and speaks in a calm, formal tone.
D) Because he is fair and patient with his students.