In a certain code language, 'oka peru' means 'fine cloth'; 'meta lisa' means 'clear water' and 'dona lisa peru' means 'fine clear weather'. In this language, which word means 'weather'?

Introduction / Context:
This coding–decoding question gives us three short phrases in an unknown language along with their English meanings. Each foreign word corresponds to exactly one English word. Our task is to identify which foreign word represents 'weather'. This is a straightforward application of matching common and unique words across the three example sentences.

Given Data / Assumptions:

• 'oka peru' means 'fine cloth'.
• 'meta lisa' means 'clear water'.
• 'dona lisa peru' means 'fine clear weather'.
• Each foreign word has a unique English meaning.
• Word order does not matter; we only care about which words appear together.

Concept / Approach:
We compare the sets of words in the foreign phrases and the English phrases. Words that appear in more than one foreign phrase will correspond to English words that also repeat. By using intersections, we can deduce the mappings for 'fine' and 'clear', and then identify the remaining unmatched foreign word in the third sentence as 'weather'.

Step-by-Step Solution:
Step 1: Compare 'oka peru' (fine cloth) with 'dona lisa peru' (fine clear weather). The common foreign word is 'peru'. Step 2: The common English word between 'fine cloth' and 'fine clear weather' is 'fine', so peru corresponds to 'fine'. Step 3: Compare 'meta lisa' (clear water) with 'dona lisa peru' (fine clear weather). The common foreign word is 'lisa'. Step 4: The common English word between 'clear water' and 'fine clear weather' is 'clear', so lisa corresponds to 'clear'. Step 5: In the third sentence 'dona lisa peru' = 'fine clear weather', we already know that peru = 'fine' and lisa = 'clear'. The remaining English word is 'weather', so the remaining foreign word must be 'dona'.

Verification / Alternative check:
We can construct the full mapping: peru -> fine, lisa -> clear, oka -> cloth, meta -> water, and dona -> weather. Substituting these back into each sentence reproduces the English meanings exactly. No contradictions arise, so the mapping is consistent and dona must be the code for weather.

Why Other Options Are Wrong:
Option A: peru stands for 'fine', not 'weather'. Option B: oka appears only in the first sentence where its partner meaning is 'cloth'. Option C: meta appears only in the second sentence and must correspond to 'water'. Option E: lisa is already used for 'clear' in two sentences.

Common Pitfalls:
A typical mistake is to guess based on unfamiliarity with the foreign words rather than methodically using overlaps. Some learners also misalign sentences and accidentally match 'peru' with 'weather' because it appears in the longer sentence. Carefully comparing which words repeat across sentences is the surest way to arrive at the right mapping.

Final Answer:
In this code language, the word for 'weather' is dona.