1.  18, 20, 23, 32, 48, 73, 109

A. 20
B. 23
C. 32
D. 48

Answer: Option A

Explanation:

The series is 18 +12 = 19; 19 + 22 = 23; 23 + 32 = 32;
32 + 4
2 = 48; 48 + 52 = 73 + 62 = 109