Problem - 4723
$\textbf{Someone's Name}$
Someone's mother has four sons: North, West and South. What is the name of the fourth son. You are asked to write down the name of the fourth son. What will you write?
$\textbf{Answer}$
What.
$\textbf{Analysis}$
This is a riddle. Pay attention to the period (instead of a question mark) after the statement "What is the name of the fourth son.".
$\textbf{Note}$
"Someone" can be an answer if the period is replaced with a question mark at the end of the above quoted sentence.