The y-intercept in the equation \( y = 0.1x + 20,000 \) represents the value of \( y \) when \( x = 0 \). In the context of this situation, when \( x = 0 \) (meaning Steven has made no sales), the equation simplifies to:
\[ y = 0.1(0) + 20,000 = 20,000 \]
This means when Steven makes no sales, his total pay (y) is simply his base salary of $20,000. Therefore, the correct response is:
A. Steven's base pay