(a) directly above the wire.
Using the right-hand thumb rule with current flowing east to west, the magnetic field above the wire points from north to south.
Source: Chapter 12, Section 12.2.2 (Right-Hand Thumb Rule), Example 12.1
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Apply the right-hand thumb rule: point the right thumb westward (direction of current). The fingers curl downward in front (south side → downward) and upward at the back. Specifically, at the point directly above the wire, the field is directed from north to south. At a point directly below, it would be south to north. This matches Example 12.1 in the textbook, which uses the identical current direction. Examiners expect you to cite the right-hand thumb rule and state the correct option clearly.