Final answer:
The electric field due to an infinite line charge distribution is radially outward and can be directed along the positive y-axis or the negative x-axis.
Step-by-step explanation:
The electric field due to an infinitely long uniform line charge distribution is directed radially outward from the positive charges and radially inward towards the negative charges. Since the line charge distribution lies parallel to the y-axis, the electric field at a point will be directed along the positive y-axis (vertically) or along the negative x-axis (horizontally). Therefore, the correct answers are:
a) The electric field at a point is radially outward.
b) The electric field at a point is directed along the positive y-axis.
c) The electric field at a point is directed along the negative x-axis.
d) The electric field at a point is radially inward.