A startup has access to a single, powerful, pre-trained language model. They want to launch two distinct products quickly: a 'Creative Co-Writer' that generates imaginative story ideas, and a 'Legal Brief Assistant' that produces formal, factually accurate summaries. The startup has a very limited budget and a tight deadline, making it impossible to fund extensive, separate training runs for each product.

Two engineers propose different strategies:

• Engineer A: Suggests creating two separate, fine-tuned versions of the model, one for each product, by continuing the training process with specialized datasets.
• Engineer B: Suggests using the single, original model for both products but controlling its output for each task by providing it with highly specific, detailed instructions and rules just before it generates a response.

Based on the startup's constraints, which engineer's strategy is more viable? Justify your reasoning by explaining the primary advantage of your chosen approach in this context.