If you only want certain options (or answer choices) can only be selected a certain number of times, you can enable Inventory Control for certain options.
Once logged in, you'll go to your Published Forms
Select the Form Menu for the Form that has the question(s) you want to add inventory to
Select Edit Form
Select Add/Edit Questions and Answers
Select the Question you want to add inventory to and then Review/Edit Question
Select the Answer Choice you want to add inventory to and then Review/Edit Answer
Select the edit icon under the Inventory Control section
Change the status to Enabled, enter how many times the answer can be chosen, and then you can decide if you want to have the number of spots available display to registrants (by checking the Display Inventory Counts publicly box) and select Save
Once saved, you can see the settings you've just enabled
Once an option is sold out or has been selected the number of times you've allowed it to be, the option will disappear from the list to registrants and there will be a memo that reads
Some items have been removed because they are no longer available.