communication methods

Hi, john sir , how are you. plz help me on following theoretical questions with a little explanation plz.

Q1. what will be the best means of communicating the message to all the employees that they will have to work overtime the next 5 days.?
a. letter
b. report
c. Memo
d. Face to face

Q2. Consider the following practices

1. draft documents and notes of a confidential nature should be shredded when finished.
2. control of confidential documents on loan from andother department should remain the responsibility of only the lending department.
3. confidential information should be numbered on distribution
4. completed documents of a confidential nature should be distributed in sealed envelopes.

Which of the above could be described as best practice with a regard to the management of confidential information?

Q.3 what is the main purpose of tabulation?
a. to ensure the figures are secure and accessible only to authorized users
b. to enable the figures to be set up on word processor
c. to make figures easier to understand
d. to organize non numerical data.

Plz also tell me what is tabulation?

Q. If a company wish to hold personal data in a permanent form for a particular purpose to whom must the company apply?

a. the deparmentof trade and industry
b. companies house
c. data protection registrar
c. local authority