In a certain code, 15789 is written as XTZAL and 2346 is written as NPSU. How will 23549 be written in that code?

The correct answer is C, NPTSL. Build a digit-to-letter table from the two given codes, then read off each digit of 23549.

From 2346 = NPSU, we get 2 = N, 3 = P, 4 = S, 6 = U. From 15789 = XTZAL, we get 1 = X, 5 = T, 7 = Z, 8 = A, 9 = L. So 23549 becomes N (2), P (3), T (5), S (4), L (9), giving NPTSL.

• A (NPTUL): the fourth digit 4 is S, not U. U belongs to 6.
• B (PNTSL): 2 and 3 are swapped. 2 is N and 3 is P, so the word must begin with N.
• D (NBTSL): 3 is P, not B. Neither sample code contains B.

Concept: this is a letter-digit substitution code in which each symbol keeps the same mapping throughout, so the two sample codes are enough to decode the third. The same disciplined mapping helps in logical reasoning and data-interpretation sections of the exam.

Trap: aspirants often look for a shifting rule instead of building the table, or they misplace digits, as option B does by swapping 2 and 3.