A company wants to use a general-purpose language model to generate enthusiastic marketing copy for a new eco-friendly water bottle targeted at young adults. The copy must highlight three features: it is BPA-free, insulated, and made from recycled materials.

Consider the two prompts below designed for this task:

Prompt A: 'Write marketing copy for a new water bottle.'

Prompt B: 'You are a marketing expert writing for a Gen Z audience. Generate an enthusiastic and catchy ad copy for our new eco-friendly water bottle. Make sure to highlight these key features: it's BPA-free, keeps drinks cold for 24 hours with its double-wall insulation, and is made from 100% recycled materials.'

Evaluate which prompt is more likely to produce the desired output. In your response, analyze the specific elements of each prompt and explain how they contribute to (or fail to contribute to) customizing the model's behavior for this specific application.