SW4, because its priority is highest and its MAC address is lower. The spanning-tree root bridge is elected by the lowest bridge ID, and the bridge ID begins with bridge priority. In the exhibit, SW4 has the lower configured priority compared with SW3, making SW4 the root bridge even before MAC address tie-breakers matter. A higher priority value is worse, not better, for root election. Cisco CCNA 200-301 v1.1 Network Access expects engineers to remember that the lowest priority wins; only if priorities tie does the lowest MAC address decide. The corrected answer is the option naming SW4. The wording in the option may be imperfect, but the device selection is driven by the lowest priority shown in the exhibit.