A salesman makes both a base salary and also a commission, which is a percentage of what he sells. Each month, if his sales total s dollars, he makes a total of 2,000 + 0.1s dollars. What does 2,000 represent?

The expression given for the salesperson's total earnings is \( 2000 + 0.1s \).

In this expression:

- \( 2000 \) is a constant amount added to the earnings.
- \( 0.1s \) represents the commission, which is 10% (or 0.1) of the sales amount \( s \).

Since the base salary is typically a fixed amount that the salesperson earns regardless of sales, and given that this fixed amount is added to the commission, we can conclude that:

**A. his monthly base salary in dollars.**

So, the correct answer is **.