The correct answer is Individual internet users.

Individual internet users are responsible for protecting themselves when they use the public internet because they control the endpoints and user actions determine many security outcomes. They must secure their devices and accounts by using strong passwords, installing updates, enabling firewalls and antivirus, and using secure networks or a VPN when on public Wi Fi.

Internet service provider supplies the network connection and may offer optional security features, but it does not manage or secure each user device or personal account and so it is not the party primarily responsible for an individual's protection on the public internet.

Managed security service provider can provide monitoring and defensive services for organizations under contract, but an MSSP does not automatically protect independent individuals using the public internet and their protections depend on the scope of the service agreement.

Cloud service provider is responsible for securing the cloud infrastructure that it operates, but customers and end users are responsible for protecting their data and endpoints when accessing cloud services over the public internet according to shared responsibility models.

Full AWS Practitioner Certification Question