The correct option is D NBWTRF
Given, MOTHER is written as ONHURF.
Here, the word 'MOTHER' is divided into three pairs of two word each and then writing each pair in the reverse order to get the word 'OMHTRE'. Now, move the 2nd, 4th and 6th letter one step forward to get the code ONHURF.
Similarly, the word ANSWER is coded as NBWTRF.
Hence, option (D) is the correct answer.