Explanation:

Given series DXB, GSI, JNP, MIW, _____
We know that alphabet position A=1, B=2, C=3 .... Z=26 .
the given series represent in the form of alphabet position
4 24 2, 7 19 9, 10 14 16, 13 9 23 , ?
From the above alphabet position series going on First number increasing 3 positions, second, decreasing in 5 position and third is
increasing 7 positions to next
, therefore? 16 4 4 (the next element of series )
? = P D D (16 4 4)