Why Correct: A simple sentence contains one independent clause with a single subject-verb unit. 'She saved money for vacation' has one subject ('she') and one verb ('saved'), with no subordinate or coordinate clauses, satisfying the definition.
Distractor Analysis: 'As she wanted to go on vacation she saved money' uses the subordinating conjunction 'as' to introduce a dependent clause, making it a complex sentence. 'She wanted to go on vacation and saved her money' uses the coordinating conjunction 'and' to join two predicates, creating a compound sentence. 'Although she saved her money, she wanted to go on vacation' begins with the subordinating conjunction 'although', forming a complex sentence.
Takeaway: Simple sentences have one finite verb and no conjunctions linking clauses; compound sentences join two independent clauses with coordinating conjunctions (for, and, nor, but, or, yet, so), while complex sentences contain one independent and at least one dependent clause introduced by a subordinating conjunction.

Why Correct: A simple sentence contains one independent clause with a single finite verb. "Pancakes are delicious only with syrup" has one subject-verb pair (pancakes are) and no coordinating or subordinating conjunction, so it qualifies as a simple sentence.
Distractor Analysis: "Pancakes are delicious when served with syrup" uses the subordinating conjunction "when," creating a dependent clause and forming a complex sentence. "If served with syrup, pancakes are delicious" begins with the subordinating conjunction "if," also producing a complex sentence. "None of the above" is invalid because the correct simple sentence exists among the choices.
Takeaway: A simple sentence can contain compound subjects or compound verbs, but it must have only one finite verb and no dependent clause; "but," "when," and "if" are conjunctions that signal either compound or complex structures.