In a certain code language, ‘RIVAL’ is coded as ‘PKTCJ’ and ‘TEXTS’ is coded as ‘RGVVQ’. How will ‘POINT’ be coded in the given language?

Correct — C. Both worked pairs move the letters alternately, and the alternation starts by falling.

Rule: letters 1, 3 and 5 shift −2; letters 2 and 4 shift +2.

RIVAL: R−2=P, I+2=K, V−2=T, A+2=C, L−2=J, giving PKTCJ.
TEXTS: T−2=R, E+2=G, X−2=V, T+2=V, S−2=Q, giving RGVVQ.

POINT: P−2=N, O+2=Q, I−2=G, N+2=P, T−2=R.
That is NQGPR — option (c).

Why the others are wrong

• (a)
  NRGOR — NRGOR has the odd positions right but moves O by +3 and N by +1. The even positions rise exactly two places, so they must give Q and P.
• (b)
  OQGPO — OQGPO drops P by only −1 and T by −5. The odd positions each fall exactly two places, which fixes N at the front and R at the end.
• (d)
  OQGOQ — OQGOQ misses three of the five letters: P must fall to N, N must rise to P, and T must fall to R.

A shift code replaces each letter by another a fixed number of places along the alphabet. That step need not be the same for every letter — here it alternates in sign, which is why a single glance at the first letter tells you nothing.

Two worked pairs are given so you can test a candidate rule on both before you use it. Write the 1-26 alphabet number under each letter of the plain word and each letter of the code, subtract column by column, and the pattern of the differences is the rule.

Key facts

• R is the 18th letter and P the 16th, so R to P is a shift of −2.
• The alternation begins with a fall, so a five-letter word ends on a fall as well.
• Both given pairs obey the same alternating rule, which is the check that the rule is right.

Common traps

• Fixing the shift from the first letter alone and applying it to all five.
• Losing the sign halfway, so the fourth letter falls where it should rise.
• Counting the shift on the code word rather than from the plain word to the code.

No directly related past PYQ was found.