A security engineer is concerned about the threat of side$-$channel attacks. The company

experienced a past attack that degraded parts of a SCADA system, causing a fluctuation to

$20,000$rpm from its normal operating range. As a result, the part deteriorated more quickly than

the mean time to failure. A further investigation revealed the attacker was able to determine the

acceptable rpm range, and the malware would then fluctuate the rpm until the part failed. Which

of the following solutions would be BEST to prevent a side$-$channel attack in the future?

A$.$ Installing online hardware sensors

B$.$ Air gapping important ICS and machines

C$.$ Implementing a HIDS

D$.$ Installing a SIEM agent on the endpoint