$\begin{array}{1 1} (a)\:(ab'-a'b)x+(bc'-cb')y+(ad'-a'd)=0\:& \:(b)\:(ab'-a'b)x+(bc'-b'c)y+(ac'-a'c)z=0\\ (c)\:(ab'-a'b)y+(bc'-b'c)z+(ad'-a'd)=0\:& \:(d)none\:of\:these.\:\:\:\:\: \end{array} $