
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
A company produces a product with a fixed cost of $20000$ yuan. For each unit of product produced, the cost increases by $100$ yuan. If the total revenue $R$ is related to the annual production $x$ by $R(x)= \begin{cases} \overset{- \dfrac {x^{3}}{900}+400x,0\leqslant x\leqslant 390}{90090,x > 390}\end{cases}$, then when the total profit is maximized, the number of units of product produced per year is $\boxed{\text{D: }300}$.

Present the answer in LaTex format: \boxed{Your answer}
user