i want my chatbot to only answer one of the given options which user will select, but user is not allowed to type anything untill user is given permission to do so. Do we have a feature like that also?

Not yet, no. There's an upcoming feature @cuddly-airline-2010 where you can re-configure the webchat during the conversation. This can be used to change the CSS stylesheet from one that shows the text composer to another stylesheet that hides it. But this feature isn't in the product yet. Keep an eye on #1111016943370113174 !