This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: COPD and Asthma, Subject name: Medicine
Which of the following is given in the maintenance of severe persistent asthma? 
Select and explain. 
A. Oral Steroid, B. Leukotriene agonist, C. Ipratropium bromide, D. Long-acting beta 2 agonist
D: Long-acting beta 2 agonist
Answer: D: Long-acting beta 2 agonist 
Explanation: LABAs improve asthma control and reduce exacerbations when added to ICS, which allows asthma to be controlled at lower doses of coicosteroids. LABAs should not be given in the absence of ICS therapy as they do not control the underlying inflammation.