Final answer:
The correct answer to which character matches exactly one character is the '?'. It is used as a wildcard in file searching and regular expressions, but does not match a backslash or period.
Step-by-step explanation:
The question is asking which character matches exactly one character in a pattern, typically used in file searching or regular expressions, with the exception of the backslash '\\' and period '.'. The correct answer to this question is B) ?. The question mark ? is a wildcard character that can replace any single character except the backslash and period.
For instance, in a search, 'fin?.txt' would match 'fine.txt' or 'find.txt' but not 'final.txt'. It is important to understand the role of special characters like wildcards when working with files, especially in operating systems like Unix, Linux, or even Windows.