Zach thinks he should get to eat the last slice of pizza because he paid for the pizza. "It's my pizza," he says to his friends. To nonverbally communicate his message through the function of accenting, Zach should

put verbal emphasis on the word "my"

Explanation:

Accenting means to use signals like sound pitch, tone gestures and facial expression to convey message like in this example Zach should put verbal emphasis on the word "my" to covey his non-verbal message.