单选题 The government is ______ and will take the necessary steps to maintain security and stability.
A. on standby B. at risk C. out of control D. on the alert

【正确答案】 A
【答案解析】[考点] 短语用法辨析
[解析] 政府严阵以待时刻准备采取必要措施以维护社会安全和稳定。on standby意为“严阵以待，时刻准备”，符合句意。故A项为正确答案。