Answer
Diagram d.
Work Step by Step
Using the right-hand rule for magnetic force, we point our thumb in the direction of velocity ($+\hat j$), our index finger in the direction of the magnetic field ($-\hat k$), and our middle finger in the direction of the magnetic force ($+\hat i$). Because the magnetic force is pointing to the right, positive charges will accumulate on the right side of the conductor and consequently the negative charges on the left side of the conductor.
Thus, the correct answer is d.
