傲慢

彼の ___ な態度は周りの反感を買った。

The correct answer is 傲慢 (ごうまん), meaning arrogant or haughty. An arrogant attitude, where one looks down on others, naturally draws resentment from those around them, making "彼の傲慢な態度" (his arrogant attitude) a perfect fit for the context "周りの反感を買った" (earned the resentment of those around him). In contrast, 怠慢 (たいまん) refers to negligence or idleness, which might cause inconvenience but not typically direct resentment towards one's persona. 自慢 (じまん) means boasting or bragging; while it can be annoying, "自慢な態度" is not a natural collocation, and "arrogance" is a stronger cause for "反感". 過信 (かしん) means overconfidence or misplaced trust; an overconfident attitude does not directly cause others' resentment in the same way as arrogance. Remember that "反感を買う" (to incur resentment) strongly suggests a negative attitude towards others.

正解は「傲慢（ごうまん）」です。「傲慢な態度」は他人を見下し、高慢な態度を取ることで、周囲から「反感を買う」原因となります。「怠慢（たいまん）」は職務を怠ることで、「自慢（じまん）」は自分のことを誇ること、「過信（かしん）」は自分を過剰に信じることです。これらは状況によっては不評を買うこともありますが、「反感」という強い感情を引き起こす「態度」としては、「傲慢」が最も適切です。