The sentence does not contain any errors in period usage is letter (A)<span> Have you read The Hobbit by J. R. R. Tolkien? Letter B is lacking a period after 'Lt'. Letter C lacks period after 'Rev' and letter D lacks a period right after the word 'Sgt.' As much as possible, contracted titles should have periods right after it.</span>
I am not sure what a joke has to do here, but anyway, a question is a question. This is a joke which answer expects a pun or a play with words. The answer to this joke is: "Checking account"
When somebody asks you what do you call drawing squares on Dracula you answer: Checking account because Dracula was a Count, and the sound produced by saying together " a count" is the same as "account".
A checking account is a deposit account held at a financial institution that allows withdrawals and deposits. Also called demand accounts or transactional accounts, checking accounts are very liquid and can be accessed using checks, automated teller machines and electronic debits, among other methods.
This joke makes reference to this popular kind of bank account.
Answer:
Dear class president,
I would like to tell you that you are the best class president. Thank you for helping students and our class. I adore our organised class because of your effort.
Yours sincerely,
.........