The answer is option 3 - Subglottic tracheal stenosis
Way down on the list of possible causes of stridor, was a very rare disorder called subglottic tracheal stenosis.The doctors ordered a CT scan of Hull’s neck, which showed a narrowing of Hull’s trachea. The pulmonologist confirmed the diagnosis.
The disorder involves a narrowing of the windpipe just below the vocal cords. If there is no known cause — as occurs in about 15 percent of cases — the condition is deemed idiopathic. The incidence and prevalence of the disorder is not known.There is no specific test for the disorder, but the narrowing can be seen on a CT scan of the neck. Medications and surgery have been used to treat the stenosis, but because the condition is so rare, it isn’t known what works best. A month later, Hull underwent a bronchial dilation, which involves expanding the airway, often through use of a balloon. The procedure restored her trachea to about 90 % functioning. In addition to coughing and clearing her throat more often than normal, Hull said she notices that colds linger. Recovery from the last one took three weeks. So far, she has not needed a second procedure
During a routine appointment in July 2011, 40 year old Dianne Hull’s primary-care doctor remarked that she seemed slightly short of breath. The doctor did not detect wheezing. He suggested using inhalers and an antihistamine before exercising. She tried the medicines but noticed no difference. She didnot smoke. She swam regularly and noticed that increasingly she felt winded even when she exerted herself only mildly. In July 2012, a chest X-ray and lung function tests were normal. Several months later, her breathing had worsened dramatically. She cleared her throat continuously, coughed frequently and struggled through exercise classes; her breathing sounded like a high-pitched whistle. Her primary-care doctor told her she had stridor, an abnormal high-pitched sound that typically indicates a partially blocked airway. The doctor suggested allergy testing. The allergist agreed that something was seriously wrong with her breathing and sent her down the hall for another round of lung function tests, which were normal.
Source : https://goo.gl/ulxvZA