Quick answer A <<<<
All horizontal lines have an equation of
y = k where k is a number. k is the y intercept.
Here are a few lines drawn for you.
y = 3
y = 1
y = - 1
y = - 2
In y = ax + b the term ax disappeared. The graph shows that x is not zero. It has many values. So the m must be zero.
A <<<<answer
