Infant angela is frustrated. her ability to wait longer to express her anger and possibly engage in a self-regulatory strategy, such as distraction, will depend on:

I believe the answer is her effortful control.

Effortful control refers to the ability to suppress a certain natural response in order to display another response.

We could see the effortful control in infants' ability to held out their anger despite having to face the situation that justify their anger.