How to disable user entry on Answer Bot in Zobot

How to disable user entry on Answer Bot in Zobot

Hi, 

I have an Answer Bot in my Zobot, here is the configuration:


I only want the user to choose 1 of the 4 the options I have provided:

When no answer found, user chooses 'I'll rephrase the question' or 'Ask a different question
When answer is found, 'user chooses 'Thanks' or 'Ask another question'

However, the user is still able to enter free text into the entry field, where the placeholder 'We are here to help you' is displayed:



How can this be disabled?

When the user enters text here it effectively  removes the user from the flow I have built.