If the sum of the 4th term and the 12th term of an arithmetic progression is 16, what is the sum of the first 15 terms of the progression?	Choose the most appropriate option:
A) 80	B) 100	C) 105	D) 120	E) 110
4th term + 12th term = 16   i.e., (a+3d)+(a+11d) = 16   Now, Sum of first 15 terms = (15/2) * [2a + (15-1)d]   = (15/2) * [2a + 14d]   = (15/2) * 16 --------------- From (1)   =120   Answer : 120
<result>D</result>
If the sum of the 4th term and the 12th term of an arithmetic progression is 16, what is the sum of the first 15 terms of the progression?