The correct answer is A. Torment.
Torture is the intentional infliction of severe pain or suffering, whether physical or mental, on a person for the purpose of obtaining information or a confession, punishment, intimidation, coercion, or any reason based on discrimination of any kind. Torture is a crime under international law and is universally condemned.
B. Chastisement is the act of punishing someone, especially a child, in order to correct or discipline them.
C. Harassment is the act of annoying or worrying someone in a persistent way.
D. Terror is a state of extreme fear and distress.
Torture is different from these other concepts in that it is always intentional and always involves the infliction of severe pain or suffering. Chastisement and harassment may involve some degree of pain or suffering, but they are not always intentional and they do not always involve severe pain or suffering. Terror is a state of extreme fear and distress, but it does not necessarily involve the infliction of pain or suffering.