Identify the sentence that uses commas correctly.
a) i also want to go to mexico and, i am saving for the trip.
b) i also want to go to mexico, and i am saving for the trip.
c) i also want to go to mexico and i am saving for the trip.
d) i also want to go to mexico, and i am saving, for the trip.

B) I also want to go to Mexico, and I am saving for the trip.  

A sentence basically has a subject, the object of the sentence or doer of the action and predicate, the verb, the adjective, etc. Sentence structures could be simple (one independent clause), compound (two independent clause with coordinating conjunction), complex (a subordinate & independent clause) and compound-complex sentences (subordinate & two independent clause). These include clauses, conjunctions, coherence and balance and even to the number of words you use in your subject and predicate. The benefit of complex or compound sentences is that it could give you more explanation on the subject or topic of the sentence. This gives you a much more understanding on what the sentence is trying to portray or to message to give.  

Athe warm welcome he received