2x - ky + 7 = 0 and 6x - 12y + 15 = 0 has no solution for;

Answer: Option C

$$\begin{array}{rl}& \text{For no - solution,}\\ & \frac{a_1}{a_2}=\frac{b_1}{b_2}\ne \frac{c_1}{c_2}\\ & 2x-ky+7=0\text{ and }6x-12y+15=0\\ & \therefore \frac{2}{6}=\frac{-k}{12}\\ & k=4\end{array}$$