MLA Handbook is the answer
It's based on a boy the author saw during her day out with her child
"<span>d. An author reveals character traits through actions, feelings, thoughts, and dialog" is the best option because it's the most common, but it should be noted that this is a creative decision. </span>
The <em>older violins</em> are more than one object, in this case its cannot be used, only their; <em>each violinist</em> could mean male or female, so it would be possible the use of his or her or their (applied for either),but there is only the latter option. The correct answer is their/their.
<em>The older violins no longer had their original parts, but each violinist played their instrument well.</em>
