Which of the following is a valid char value?

A) '$_'
B) '%'
C) 'n\'
D) "a"

Option B is a valid char value as it represents a single character enclosed in single quotes. Option A is not valid as the '_' symbol is not allowed in a char value. Option C is not valid as the backslash needs to be escaped to be included in a char value. Option D is valid but is a string value enclosed in double quotes, not a char value.