Which of the Following Statements Is a "True" Statement

Multiple Choice

Which of the following statements is a "true" statement?

A) The world's food supply could be grown in a flower pot, if the law of diminishing returns did not hold!
B) The law of diminishing returns is another example of the statement, "That's okay in theory but not in practice."
C) No factor of production could ever be employed in such large quantities as to produce a marginal product that is negative.
D) Total product must always go up when a firm hires more inputs.