Answer:
The simplest way to ensure that APIs are only used by legitimate users is to require the
use of authentication. API keys are one of the most frequently used methods for this. If an
API key is lost or stolen, the key can be invalidated and reissued, and since API keys can be
matched to usage, Cynthia's company can also bill customers based on their usage patterns
if they want to. A firewall or IP restrictions may be able to help, but they can be fragile;
customer IP addresses may change. An intrusion prevention system (IPS) can detect and prevent
attacks, but legitimate usage would be hard to tell from those who are not customers
using an IPS.
A. Require authentication.
B. Install and configure a firewall.
Step-by-step explanation: