1 is B, as x is being affected by an exponent so the points would not line up to be a straight line but a curve.
2 is D, since y is equal to only the y intercept is not changing so the gradient is 0.
3 is C. It is the standard linear equation formula and would be represented as a straight line.
4 is A. X is not changing so this is an example of x = d or a vertical line.
