Answer:
The correctly punctuated sentence is:
Juan plans to travel from Santa Fe, New Mexico, to Boulder, Colorado, for business.
Explanation:
Commas are punctuation marks used to show a brief pause or break in transition in a sentence. There are some rules to observe when using a comma, starting with the rule obeyed in the answering of this question, I will briefly explain them.
1. Commas are used to set off all geographical names: in the sentence; 'Juan plans to travel from Santa Fe, New Mexico, to Boulder, Colorado, for business', after 'Santa Fe', there is the introduction of a geographical name 'New Mexico', and by the rule, it is preceded by a comma. The same rule is observed with 'Boulder', introducing 'Colorado'. Also the use of a comma after 'Colorado' before 'for' is important, because it tells a change in transition, from naming a place, to the reason for going there, without which the phrase 'Colorado for business' will be considered just as one idea (the name of a place)
Other rules of using commas include:
a. commas are used to separate two or more independent clauses, when they are joined by the conjunctions: and, but, for, or, nor, so, or yet. Example, We wanted to come over but, the rain was heavy.
b. commas are used after introductory clauses, phrases, or words coming before the main sentence, e.g. Moreover, we still did it.
c. commas are used to set off and to end non-essential parts of a sentence. E.g. The big house, which was built long ago, was demolished.
d. commas are used to separate contrasting coordinating elements in a sentence to show a distinct pause or shift.
Example, Although he recently has an accident, he ran fast.
I suggest you check out the other rules of using comma, to help your understanding.
