How to ensure that the person who is submitting the form is the actual person?

What kind of security features are available to ensure that the person who is submitting the form is the actual person?

You can add a reCAPTCHA field to your form. We have four options to prevent SPAM submissions.

First one of these options is our CAPTCHA field which is located under the basic form elements. Please check our user guide: How to Add a Captcha Field

The second one is Google ReCAPTCHA widget.

The third one is Drawing CAPTCHA widget.

And as the last one is Unique Submissions on a Form. You can also add more striction to your form by Unique Submissions feature.

I hope one of these four alternatives meets your needs.