Acting choices are the ways you have chosen to act your part. For example, the way you walk and talk as the character are acting choices. Great choices are those that are most viable for the role and are most creative and unique. To get better at making acting choices, spend more time studying the script and using your imagination to create the physical character so it is apt for the playwright's concept and unique to your portrayal.
Creating the physical character is the truly creative art of acting. The playwright has already created the emotional character. Sometimes the playwright also specifies certain physical characteristics of the characters. You use those and add your own twist on them to make your performance unique. But you always remain true to the playwright's concept of the role. That you do not meddle with. For example, I once saw a play in which one of the principle roles was changed from male to female, which, according to the director of this production, allowed her(the director) to make the play a statement about feminism. Problem was that both the character and the message of the play as presented by this production was not anything like the playwright's intent. Bad creative choices.
The emotional character has been determined by the playwright. You don't get to make a lot of choices in this area of your performance. Most of your responses will be those that the playwright planned on. If you are a highly sensitive and well trained Ta0 actor (see Tao and the Art of Acting at my web site), some of the emotional responses you have in your performance will not have been anticipated by the playwright. That is OK as long as they do not change the intent of the play. It is you, yourself, your emotional responses that make your performance unique, vulnerable and dynamic. Excellent choices for the actor!