A regular expression is a method used in programming for pattern matching. Regular expressions provide a flexible and concise means to match strings of text. Following is the answer: import redef is_allowed_specific_char(string): charRe = re.compile(r'[^a-zA-Z0-9.]') string = charRe.search(string) return not bool(string) print(is_allowed_specific_char("ABCDEFabcdef123450")) print(is_allowed_specific_char("*&%@#!}{")) Answer: a. re is a part of the standard library and can be imported using import re. Answer: a. It will look for the pattern at the beginning and return None if it isn't found. Answer: d. This function returns the entire match.