Which of the following is a methylxanthine group of bronchodilators?

Correct option is B

Aminophylline is a methylxanthine, a class of bronchodilators that work by relaxing the smooth muscles of the bronchi, thus helping in the management of asthma and chronic obstructive pulmonary disease (COPD).
Explanation of options: (a) ✘ Incorrect. Terbutaline is a beta-agonist bronchodilator, not a methylxanthine. (b) ✔ Correct. Aminophylline is a methylxanthine derivative used as a bronchodilator. (c) ✘ Incorrect. Salmeterol is a long-acting beta-agonist, not a methylxanthine. (d) ✘ Incorrect. Ipratropium is an anticholinergic bronchodilator, not a methylxanthine.