Which clause is independent?
a. because i tend to lose things.
b. even if the closet is the best place for them.
c. whenever i put them away in a closet.
d. there on the table is the box.

That is letter D: There on the table is the box.. The sentence could still stand on its own even when the subject is put first, which even made more sense: The box is there on the table.  

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.