What is the initial value of 10 in this equation?

Slope-intercept form:  y = mx + b

(m is the slope, b is the y-intercept or the y value when x = 0 --> (0, y) or the point where the line crosses through the y-axis)

The initial value is the y-intercept, or it's like the starting point.

If the equation has an initial value of 10, b = 10

Your answer is the 2nd option because the y-intercept is 10