A line passes through the points (7, 10) and (7, 20). Which statement is true about the line? It has a slope of zero because in the formula is zero, and the numerator of a fraction cannot be zero. It has a slope of zero because in the formula is zero, and the denominator of a fraction cannot be zero. It has no slope because in the formula is zero, and the numerator of a fraction cannot be zero. It has no slope because in the formula is zero, and the denominator of a fraction cannot be zero.

Slope formula: [tex] \frac{y2-y1}{x2-x1} [/tex]
Apply. 
[tex] \frac{20-10}{7-7} = \frac{10}{0} = [/tex] undefined (No slope) 

Thus, that answer is: Choice D. 

If you're wondering why C isn't this answer, it's because  it doesn't matter if 0 is the numerator of a fraction. If it was, then the slope would be 0 regardless. However, if 0 takes place in the denominator, the slope will be undefined; there will be no slope.