What is the angle between an equipotential surface and electric lines of force (in $^{\circ}$)?

The figure shows two equipotential lines in the $XY$ plane for an electric field. The scale is shown. The $X$-component $E_x$ and $Y$-component $E_y$ of the electric field in the space between the equipotential lines are respectively:

Describe schematically the equipotential surfaces corresponding to
$(a)$ a constant electric field in the $z$-direction,
$(b)$ a field that uniformly increases in magnitude but remains in a constant (say,$z$) direction,
$(c)$ a single positive charge at the origin,and
$(d)$ a uniform grid consisting of long equally spaced parallel charged wires in a plane.

The diagrams below show regions of equipotentials. $A$ positive charge $q$ is moved from $A$ to $B$ in each diagram.

$A$ uniform electric field is directed along the $Y$-axis. Consider point $A$ as the origin $(0,0) \text{ m}$. The coordinates of point $B$ are $(0,2) \text{ m}$. The coordinates of point $C$ are $(2,0) \text{ m}$. If the electric potentials at points $A, B,$ and $C$ are $V_A, V_B,$ and $V_C$ respectively,which of the following options is correct?

Electric field is always ...... to the equipotential surface at every point. (Fill in the gap)