Study the following information carefully and answer the questions given below. Five persons A, B,C, D and E (but not necessarily in the same order) h...

Study the following information carefully and answer the questions given below. Five persons A, B,C, D and E (but not necessarily in the same order) have different designations i.e., General Manager (GM), Deputy General Manager (DGM), Assistant Manager (AM), Section Officer (SO), and Clerk in a company. The order of seniority is the same as given above i.e., GM is the senior-most designation and Clerk is the junior-most designation. Each person has different number of pens – 19, 23, 35, 39 and 51 but not necessarily in the same order. The one who has prime number of pens is not the senior most person but two designations senior to D. C is junior to D. The one who has 39 pens is just senior to E. The difference between the pens of E and C is 4. D has 12 pens more than C. B is junior to the one who has 39 pens. Question: What is the designation of A?