Final answer:
Dexter's opening of a laundry business increased profits for his business, created greater job opportunities in the community, and likely resulted in cleaner and fresher clothes for customers.
Step-by-step explanation:
The effect of Dexter opening a laundry business can be understood through a few different impacts presented in the narrative clues. Firstly, the fact that Dexter would 'return next day to his prospering laundries' indicates that by opening a laundry Dexter was able to increase profits for his business, thereby suggesting a positive financial outcome (A). Secondly, the larger socio-economic impact can be seen where the narrative hints at the wider availability of goods and productivity improvements, akin to the historical effects of industrialization on textiles, which implies that Dexter's laundry would contribute to greater job opportunities in the community (D). Lastly, although not explicitly mentioned but inherently tied to the function of a laundry, there would likely be benefits for customers in terms of having 'Cleaner and fresher clothes' (B).