Two long straight parallel lines, #1 and #2, carry uniform positive linear charge densities. The charge density on line #2 is twice as great as the charge density on line #1. The locus of points where the electric field due to these lines is zero is along a line between the lines closer to line #2 than line #1.

at a point midway between the lines.

along a line between the lines closer to line #1 than line #2.

along a line perpendicular to lines #1 and #2.