Electronic configuration of four elements A, B, C and D are given below : 

A. 1s22s22p6

B. 1s22s22p4

C. 1s22s22p63s1

D. 1s22s22p5

What is the correct order of elements based on their increasing electron affinity?

1. A < C < B < D 2. A < B < C < D
3. D < B < C < A 4. D < A < B < C