Final answer:
The option that is not an example of the productive nature of language is a child making up nonsensical words for objects (b), as they may not effectively communicate or express new ideas, unlike the creation of poems or unique narratives in the other examples.
Step-by-step explanation:
The productive nature of language indicates the ability of language to innovate and create new expressions or ideas. When assessing which option is not an example of this creativity, a teacher asking students to write their own original poems (a) is clearly productive, as it involves creating new artistic expressions. Similarly, an author with the realization that they can describe any story uniquely (c) is exercising the productive attribute of language by crafting original narratives. However, a child making up nonsensical words for objects (b) might not be an example of productive language use, as they are not necessarily communicating or expressing new ideas effectively. The creative use of language implies that a word or phrase conveys a concept that can potentially be shared with others, not just random sounds.