Correct Answer: MORU

Solution : Let's check the options –
First option: BDGK; B + 2 = D; D + 3 = G; G + 4 = K
Second option: JLOS; J + 2 = L; L + 3 = O; O + 4 = S
Third option: NPSW; N + 2 = P; P + 3 = S; S + 4 = W
Fourth option: MORU; M + 2 = O; O + 3 = R; R + 3 = U

So, the fourth option is different from the other three as the difference in the place values of the third and the fourth letters is 3 instead of 4. Hence, the fourth option is correct.