def get_username(first, last): s = first + "." + last return s.lower() def main(): first_name = input("Enter your first name: ") last_name = input("Enter your last name: ") username = get_username(first_name, last_name) print("Your username is: " + username) if __name__ == "__main__": main()

Refer to Code Example 4-1: What arguments are defined by the get_username() function?

	a.	first, last
	b.	username
	c.	first_name, last_name
	d.	s, first, last