Final answer:
The correct sentence for formal writing is 'Gap's product development office is located at 55 Thomas Street, New York, New York.' because it uses the full forms of the location details. The use of abbreviations is generally considered less formal.
Step-by-step explanation:
The correct sentence suitable for formal writing is: 'Gap's product development office is located at 55 Thomas Street, New York, New York.' This is because when written formally, it is recommended to write out the names of states and cities in full, and not use abbreviations. The abbreviation 'St.' in option C is informal, and the abbreviations 'NY, NY' in option B are likewise informal.
Additionally, as the reference information provided states, 'if someone lives in San Francisco, then they live in California. If someone lives in California, then they live in the United States. Hassan lives in San Francisco. Therefore, Hassan lives in the United States', it emphasizes that the location details should be written in a full and proper hierarchical order, all the way from the specific street to the state and country, for the sake of clarity and formality.
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