Well by using the process of elimination C) Romantic Techniques would no be your answer. So your left to A) and B). This is where is gets tricky. In some cases Mozart was known for both. But still people may argue over Complex Ornamentation and Memorable Melodies. But you have to think it like this Mozart pieces were very complex. But keep in mind in some cases your answer will be opinion based so therefore the answer is A and B. But in this situation your answer would be A) Complex Ornamentation.