Mathematics

Problem

If the lines

\frac{x-2}{1} = \frac{y-3}{1} = \frac{z-4}{-k}

and

\frac{x-1}{k} = \frac{y-4}{2} = \frac{z-5}{1}

are coplanar, then

k

can have a. any value b. exactly one value c. exactly two values d. exactly three values