The correct answer is flooding.
Flooding is a psychological technique used in overcoming fears and phobias.
The technique is based on the idea that any kind of phobia is a learned fear and it has to be unlearned by exposure to the things one fears.
Flooding was invented by psychologist Thomas Stampfl in 1967.
Jennifer is afraid of heights, so the heights are her phobia, her learned fear. By being put on a ladder, she would have to face her fear by exposure, standing on the ladder for a long time and realizing that it's not really that dangerous. This prolong exposure to her fear would reduce it in the end, the fear of heights would be unlearned and Jennifer would replace the fear with relaxation, and won't be afraid of heights any longer.