A) BASIC DDULE

    LEADER NHCGGU

A)  SPRING  UNUFRC

     MOBILE OMEFPA

The first, third and fifth letters in the word are moved two, three and four steps forward respectively while the second, fourth and sixth letters are moved two, three and four steps backward respectively to obtain the corresponding letters of the code.

C)  ROAD URDG

SWAN VZDQ

A) CLOUD GTRKF

SIGHT WGJHV

The letters of the word are written in the reverse order and in the group of letters so obtained, the first, third and fifth letters are each moved three steps forward while the second and fourth letters are each moved one step backward to get the code.

A) GERMINATION IMGRENNOAIT

ESTABLISHED  BAETSLDEIHS

The middle letter remained unaltered in the code. Let us label the five letters before the middle letter as well as those after it, from 1 to 5. Then, the code contains the letters of each group in the order 5, 4, 1, 3, 2.

C) CONDEMN CNODMEN

TEACHER TAECEHR

The last letter of the word remains unaltered in the code. The first six letters of the word are divided into two groups of three letters each and then, in each group, the last two letters are written in a reverse order.

A) COVALENT  BWPDUOFM 

     FORM PGNS

the first half and second half of the word are written in the reverse order and then each letter of the group so obtained is moved one step forward to get the code.

SILVER MJTSFW

A)  HAND SZMW

 MILK  NROP

A letter is the nth letter from the beginning of the English alphabet, then in the code the corresponding letter is the nth letter from the end.

C) RAIL KCTN 

SPEAK CGRUM

Codes are written in the reverse order,  each letter is moved two steps forward to get the code. then

AVOID IOVAD KQXCF

A) THANKS SKNTHA

The code is formed by first writing the last three letters of the word in a reverse order, followed by the first three letters in the same order.

STUPID DIPSTU