I threw the ball to Yvonne. where is the direct object

Yvonne

Explanation:

In grammar, the doer of the action in a sentence is the subject, while the receiver of the action is the object.

There are direct object and indirect object and the difference is the direct object is found in a simple sentence and is the one that receives the action in that sentence.

Therefore, based on the simple sentence,

"I threw the ball to Yvonne.*, the direct object is Yvonne because she is the receiver of the ball