In a certain code language, (A) “pit na som” means “bring me water”, (B) “na jo tod” means “water is life”, (C) “tub od pit” means “give me toy” and (D) “jo lin kot” means “life and death”. Which code word in this language represents the word “is”?

Introduction / Context:
This coding and decoding question uses a simple artificial language where each word is represented by a unique code word. You are given four coded sentences along with their English meanings. Your task is to deduce which specific code stands for the English word “is”. These questions check your ability to use logical intersections and eliminations.

Given Data / Assumptions:
Sentence A: “pit na som” means “bring me water”.
Sentence B: “na jo tod” means “water is life”.
Sentence C: “tub od pit” means “give me toy”.
Sentence D: “jo lin kot” means “life and death”.
Each code word represents exactly one English word, and each English word always uses the same code.
Different English words use different code words.
We must find which code word among jo, na, tod and lin stands for “is”.

Concept / Approach:
The key idea is to look for common English words across two sentences and match them with common code words across the corresponding codes. Once you identify some word code pairs, you can gradually eliminate candidates and isolate the code for “is”. This is essentially a puzzle of matching sets of three words with sets of three code tokens.

Step-by-Step Solution:
Step 1: Compare sentence A and sentence B. Sentence A, “pit na som”, means “bring me water”. Sentence B, “na jo tod”, means “water is life”. Step 2: The common English word between these two sentences is “water”. The common code word must therefore represent “water”. Step 3: The code words in sentence A are {pit, na, som} and in sentence B are {na, jo, tod}. The only common code word here is “na”. So “na” corresponds to “water”. Step 4: Now compare sentence B and sentence D. Sentence B means “water is life” and sentence D means “life and death”. The common English word here is “life”. Step 5: The code words in sentence B are {na, jo, tod}, and in sentence D are {jo, lin, kot}. The common code word is “jo”. Thus, “jo” stands for “life”. Step 6: In sentence B, “na jo tod” corresponds to “water is life”. We now know that “na” is “water” and “jo” is “life”. The remaining code word in this sentence, “tod”, must represent the remaining English word “is”.

Verification / Alternative check:
To verify, check for any contradictions. In sentence C, “tub od pit” means “give me toy”. None of the words “give”, “me” and “toy” overlap in meaning with “water”, “life” or “is”, and the code words in sentence C do not reuse “na”, “jo” or “tod”. In sentence A, we already have “pit na som” mapped to “bring me water”, and “na” is “water”, leaving “pit” and “som” for “bring” and “me”. Everything remains consistent. Thus, there is no conflict, and “tod” correctly stands for “is”.

Why Other Options Are Wrong:
jo: This code word has been mapped to “life”, not to “is”, from the comparison of sentences B and D.
na: This code word represents “water” as deduced from sentences A and B.
lin: This code word appears only in sentence D, which means “life and death”, and it matches either “and” or “death”, not “is”.

Common Pitfalls:
A common mistake is to try to guess the mapping based on partial matches without fully using all the given sentences. Another error is to ignore the assumption that each word has a unique code, which can lead to confusion. Always use set intersections for common words and then assign remaining code words by elimination.

Final Answer:
The code word that represents “is” in the given language is tod.