Final answer:
The correct punctuation of the sentence is option a) They used reduced scale, which is the process of recreating, in a confined area, natural views of mountains and rivers.
Step-by-step explanation:
The correct punctuation of the sentence is option a) They used reduced scale, which is the process of recreating, in a confined area, natural views of mountains and rivers.
This option includes the use of commas to set off the nonessential clause "which is the process of recreating, in a confined area, natural views of mountains and rivers". This clause provides additional information about the reduced scale and can be removed from the sentence without changing its meaning. The commas help to indicate that the clause is not essential to the overall meaning of the sentence.