Question 481604
A the slope of any horizontal line is 0 ... <font color=red>True</font> 
B the slope of any vertical line is 1  ... <font color=red>False. Slope is undefined.</font>
C the parallel lines have the same slope  ... <font color=red>True</font>
D the slope can be found using any two points on a straight line  ... <font color=red>True</font> 



So the answer is choice B.