A linear relationship with no slope would be a vertical line, meaning the equation would have no x-term (or the x-term would have a coefficient of 0). So, the correct options are:
A. x = 3
B. y = 3
Both A and B represent a linear relationship with no slope. Option C and D both have x and y terms and can be rearranged to y = -x + 1 (for option C) and y = -x + 1 (for option D), both of which have a slope of -1.