(c) Used for a word character
Reason: In java, the "\w" regex is used to match with a word character consists of [a-zA-Z_0-9]. For example, \w+ matches one or more word character that is same as ([a-zA-Z_0-9] +).
The regex \W, \s, and \S are used for a non-word character, a whitespace character, and a non-whitespace character, respectively. Hence, the \w regex is used for a word character.