In the Table Below, Which of the Following Is Not

In the table below, which of the following is not true?

A) the marginal product of the 4^th worker is the same as the marginal product of the 6^th worker.
B) the marginal product of the 7^th worker is half that of the 4^th worker.
C) the marginal product of the 8^th worker is -10.
D) The 8^th worker hired is inherently less productive than the other workers hired before him.