Answer:
The correct answer option is 0.
Step-by-step explanation:
When a line is parallel to the x-axis, its slope is zero.
Here in this case, we have a graph of a horizontal line x = -3 which is parallel to the x axis.
Therefore, the slope of this line will be zero as no change in the value of y is seen because the value of x is constant at each point of the line.
