In a certain code language, '3a, 2b, 7c' means 'Truth is Eternal';

'7c, 9a, 8b, 3a' means 'Enmity is not Eternal'  and

'9a, 4d, 2b, 8b' means 'Truth does not perish'.

Which of the following means 'enmity' in that language ?

From the given information :

how can you go = ja da ka pa....(1)
can you come here = na ka sa ja...(2)
come and go = ra pa sa....(3)
from (1)&(2), can you = ja ka...(4)
from (2)&(3), come = sa...(5)
Using (4)&(5) in (2), we get here = na.

The letters of the word are reversed in order, taking two at a time, to obtain the code.

The letters at odd positions are each moved two steps backward and those at even positions are each moved two steps forward and the obtained code is reversed to get the corresponding letters of the code.

Z Code⇒26⇒262⇒13⇔133 =2197

$$\begin{gathered} R Code ⇒18⇒182⇒9 ⇔93 =729 \\ \end{gathered}$$

Similarly, J Code ⇒10⇒102⇒5⇔53=125

 123456PROBLE7M⇒716253MPERLO4B

Similarly, 123456NUMBER7S⇒716253SNRUEM4B

Answer : 5

Explanation : Given that, For each letter in the word (FLIES) there is a code written and also that code is denoted by either 1 , 2, 3, 4 or 5 

Apply the below code, It exactly matches the Given Condition

Letters at odd- numbered places shift three positions backward and letters at even-numbered places shift two positions forward as in English alphabet.

Here, Odd- Numbered Places F, I , S shift three positions backward in English Alphabet.

Even- Numbered Places L, E shift two positions forward in English Alphabet.

Therefore, exact code for the underline letter (F) is C.

So the Answer is 5.

For convenience , we assign numbers to each word :

allow  children  to  play  on  the  ground

   1         2      3    4      5    6       7

It has been coded as : 

play  allow  on  children  the  to  ground

  4       1     5        2       6    3      7

------------------------------------------------------------------------

Hence the given code is :

the  do  open  not  electric  touch  wires

 4     1      5     2       6         3       7

Now arranging them as 1 2 3 4 5 6 7, we have "do not touch the open electric wires'.

Hence, option (3) is correct answer.