The correct option is A Hydathode.
The loss of water in the form of droplets from margin of leaves is called as guttation. Guttation usually occurs in the plants growing in the warm and humid climate. It usually occurs during night or in the morning when the absorption of water exceeds that of the transpiration. Due to which, root pressure is increased in xylem and water comes out through hydathodes. Thus, option B is the correct answer.