Final answer:
The plural form of 'le cahier' is 'les cahiers'.
Step-by-step explanation:
The correct plural form of the word 'le cahier' is les cahiers.
In French, the word 'le' means 'the' in English and 'cahier' means 'notebook'.
When changing 'le cahier' to the plural form, 'les' is used for the definite article 'the' and 'cahiers' remains the same as 'notebooks'.
Learn more about French plurals