Which sentence is most clearly written?

The first sentence is the clearest because it employs appropriate punctuation, including a comma before the phrase "which was set at the back of the property" and another before "including a shed." This punctuation helps to clarify that the descriptive information about the house and its outbuildings is distinct and provides additional context without confusing the reader.

In contrast, the second sentence lacks a comma before "had," which creates a run-on feel and makes it less clear where one idea ends and another begins. Additionally, the absence of commas around "including a shed" might lead the reader to misinterpret the relationship between the outbuildings and the house. The clarity of communication is essential in effective writing, and the correct punctuation in the first option ensures that the sentence is easy to read and understand.