The key difference is that an Intrusion Prevention System (IPS) is installed in line with network traffic, allowing it to actively block threats. In contrast, an Intrusion Detection System (IDS) only monitors and alerts without actively blocking traffic.

Breakdown of Options:

A. An IPS needs to be installed in line with traffic and an IDS does not. ✅ Correct answer. IPS actively prevents threats, while IDS only detects them.

B. An IPS is signature-based and an IDS is not. – False, both can use signature-based detection.

C. An IPS is less susceptible to false positives than an IDS. – False, both can produce false positives, depending on configurations.

D. An IPS requires less administrative overhead than an IDS. – False, IPS requires more administrative effort due to real-time blocking decisions.