Before you can pick the correct one, you have to review in your mind what you know about the electric field. (Or what you SHOULD know about it.)
-- The field lines show where a teeny tiny POSITIVE charge wants to go when you put it down anywhere.
-- A teeny tiny POSITIVE charge always wants to get AWAY from other positive charges, and it wants to go TOWARD negative charges.
That's all you need. Now let's look at the pictures. I want to look at them from the bottom up:
(D). ... No. The arrows show that the tiny positive test charge wants to go AWAY from the negative (blue) charge and TOWARD the positive (red) charge. That's wrong.
(C). ... No. The arrows show that the tiny positive test charge wants to go AWAY from any negative charges. That's wrong.
(B). ... No. The arrows show that the tiny positive test charge wants to go AWAY from BOTH the negative charge AND the positive charge. That's wrong.
(A). ... YES ! The arrows show that the tiny test charge wants to go away from the positive charge, and toward the negative charge. That's exactly right.
(That's why I wanted to do them backwards ... because the first picture on the page is the correct one.)
