When your form is multi-step, you can use the "Jump to" option in the logic to show or hide the next question based on previous answers.
If your question is a multi-choice field, you should add a condition for each option.
For example, you want to show the email field if the answer to the multi-choice question is option 1 and option 2. So the logic is:
if the answer is option 1,
if the answer is option 2