A sphere of radius $r$ has electric charge uniformly distributed in its entire volume. At a distance $d$ from the centre inside the sphere $(d<r)$ the electric field intensity is directly proportional to

$ABC$ is an equilateral triangle. Charges $+q$ are placed at each corner. The electric field intensity at the centroid of triangle will be

Point charges each of magnitude $Q$ are placed at three corners of a square as shown in the diagram. What is the direction of the resultant electric field at the fourth corner ?

If electric lines of force in a region are represented as shown in the figure, then one can conclude that the electric field is