You can see that in Response, there are 2 S's and 2E' , similarly in FFMOPQRR ,there are 2 F's and 2 R's .
So you can see that E is near by F and R is near by S.
So vowel is actually changing to +1 and constant is changing to -1.
And then word is arranged to alphabetical order.
R -1 = Q
E+1 = F
S -1 = R
P -1 = O
O +1 = P
N -1 = M
S - 1 = R
E + 1 = F
so QFROPMRF when arranged in alphabetical order , it will be FFMOPQRR.
APPROACH = BOOQPBBG
When arranged in alphabetical order , it will be BBBGOOPQ.