The total earnings of the salesman each month are expressed as \(2,000 + 0.1s\), where \(s\) is the total sales in dollars.
In this equation:
- \(2,000\) is a fixed amount that he receives regardless of his sales, which is characteristic of a base salary.
- \(0.1s\) represents the commission he earns, which is a percentage (10% in this case) of his sales.
Thus, the $2,000 represents his monthly base salary.
Therefore, the correct answer is: • A. his monthly base salary in dollars