Answer
UP
Work Step by Step
Electric field lines point away from positive charges and towards negative charges.
Here, because the two positive point charges are in the same plane/axis, the $x$-component of $\vec{E}$ will cancel out. Since there is a negative test charge above the dot, the electric field caused by this negative test charge points toward it in the upward direction.
Since both the positive test charges cancel out, the only electric field at that point in space is due to the negative test charge, and therefore the electric field vector points UPWARD.
