Concept:The nth term of an Arithmetic Progression is given by Tn=a+(n−1)d.Explanation:Here, first term a=−20 and fourth term T4=37.For the fourth term, T4=a+3d.So, −20+3d=37.Add 20 to both sides: 3d=37+20=57.Divide both sides by 3: d=357=19.Answer:The common difference is 19, which is option C.