Explain the sentence: 'Work expands so as to fill the time available for its completion' .

• A. The more work there is to be done, the more the time the needed.
• B. Whatever time is available for a given amount of work , all of it will be used.
• C. If you have more time, you can do more work .
• D. If you have some important work to do, you should always have some additional time.