How to create a Single Line Field with only one acceptable answer (as alternate to picture verification code)?

How to create a Single Line Field with only one acceptable answer (as alternate to picture verification code)?

Greetings,

We have had some of our customers complain about how it is very difficult to read the verification code from Zoho, and that it doesn't work on Apple Safari web-browser (both Windows and Mac versions). As an alternative to the verification code, I would like to implement a Single Line Field that is presented in the form of a question with only one acceptable answer; for example, "What is the ZIP code of Company Co.?" with an answer of "123456", or "What phone number should you dial for assistance (10-digit without ext., ex. 8002848884)" with an answer of "1231231234" (which happens to be printed in big 16pt bold font right under the Submit button for the form). It would obviously be a required field, but must be a very exact user input value.

Would appreciate assistance on this. Thanks!