Geography · Indian Climatology

With reference to cold wave conditions in India, consider the following statements: I. In hilly regions, a cold wave may be declared when the minimum temperature of a station falls to 10°C or below. II. Over the plains, a severe cold wave condition may be declared when the minimum temperature falls to 2°C or lower. III. La Niña conditions generally lead to warmer winters in northern India and hence reduce the likelihood of cold wave events. Which of the statements given above are correct?