Gwyneth and George have a catering company. Their profits are given by the function $P(t)$, where $t$ is the months since they opened for business and $P$ is given in dollars.
If they don't start making money until 8 months into their business venture, which of the following statements must be true?
I. The point $(8, 0)$ is on the graph of $P'(t)$.
II. The graph of $P'(t)$ is below the $t$-axis until $t = 8$ and above the $t$-axis after $t = 8$.
III. $P'(t)$ is measured in dollars per month.