Final answer:
The correct answer is 'Cc:'. 'Cc:' stands for 'Carbon Copy' and is used to indicate that a person other than the writer copied on the letter or memo.
Step-by-step explanation:
The correct answer is a) Cc:.
The 'Cc:' stands for 'Carbon Copy' and is used to indicate that a person other than the writer copied on the letter or memo. It is a way to inform additional recipients about the correspondence.
For example, if you are writing a memo to your boss but want to keep a colleague informed as well, you can use 'Cc:' followed by the colleague's name or email address.