This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2017, Subject name: Pharmacology
Ritodrine is a:- 
Select and explain. 
A. b 2 agonist, B. b antagonist, C. a agonist, D. a 1 antagonist
A: b 2 agonist
Answer: A: b 2 agonist 
Explanation: * Selective b2 stimulants : salbutamol, terbutaline, salmeterol, formoterol and ritodrine * b2 agonists can be used for preterm labour as they cause uterine relaxation. * b2 Stimulators Used in preterm labour : RITODRINE ISOXSUPRINE