Based on the information provided, if only paper clips W and X moved toward the magnet, it indicates that the magnet is effective for those clips which are at distances of 1 centimeter (W) and 4 centimeters (X). Since paper clip Y (at 5 centimeters) and Z (at 7 centimeters) did not move, it suggests that the magnet does not work well for any paper clips beyond 4 centimeters. Therefore, the correct answer is:
A. 4 centimeters away.