Question logic allows you to crate path for your respondents. For example if respondent selects answer choice A he will see page 3, if he selects B he will see page 4 and if he selects both A and B he will see pages 3 and 4.
To add question logic :
Multiple choice question logic hides pages for which you set logic and shows them if respondent selects answer choice with the logic.
NOTE. You have to divide your survey into pages before you start to design question logic.
Option available in Starter, Standard, Professional and Enterprise plan.