The correct answer is A. arrogant.
Careful is to cautious as boastful is to arrogant. This is because careful and cautious are both synonyms of the word “wary,” which means to be on one’s guard or to be careful. Similarly, boastful and arrogant are both synonyms of the word “prideful,” which means to have or show an excessively high opinion of oneself.
Option B, humble, is incorrect because humble means to be modest or to have a low opinion of oneself. This is the opposite of arrogant, which means to have or show an excessively high opinion of oneself.
Option C, joyful, is incorrect because joyful means to be happy or full of joy. This is not related to the concept of being careful or cautious.
Option D, suspicious, is incorrect because suspicious means to be doubtful or mistrustful. This is not related to the concept of being boastful or arrogant.