How to allow the application to communicate back to the on premise equipment

Question

One of the questions in a AWS practice exam is as below:

You are a solutions architect who has moved to a manufacturing company who has very legacy applications. One of these applications needs to communicate with services which are currently hosted on premise. The people who wrote this application have left the company and there is nothing to document how the application works. You need to ensure that this application can be hosted in a bespoke VPC but still be able to communicate to the back end services which are hosted on premise. Which of the three answers below will allow the application to communicate back to the on premise equipment without the need to reprogram the application?

Answer 1

The connection would need to be either via AWS Direct Connect or a VPN Connection, both of which connect to an Amazon VPC via a Virtual Private Gateway rather than an Internet Gateway.

It would be possible to establish a Software VPN connection back to on-premise, which would require software configuration, an Internet Gateway and a Public IP address (for the Software VPN). However, the provided answers make no mention of a Software VPN.